KR101003836B1

KR101003836B1 - Method for manufacturing nano structure

Info

Publication number: KR101003836B1
Application number: KR20050091588A
Authority: KR
Inventors: 김기범; 박상현
Original assignee: 재단법인서울대학교산학협력재단
Priority date: 2005-09-29
Filing date: 2005-09-29
Publication date: 2010-12-27
Also published as: WO2007037658A1; KR20070036499A

Abstract

The present invention is to provide a method for producing a nanostructure that can ensure the size and depth uniformity of the nano-pores formed when the material layer is oxidized through anodization, the present invention is to form a silicon oxide film on a silicon wafer step; Selectively etching the silicon oxide layer to form a trench having a sidewall shape having a gentle curvature; Forming a conductive film on the silicon oxide film including the trench; Forming an aluminum thin film on which the nanopore array is to be formed on the conductive film; Planarizing the surface of the aluminum thin film through chemical mechanical polishing; Oxidizing the aluminum flattened surface through an anodization process to form alumina having nano-pores; Further proceeding the anodization excessively to remove alumina under the nanopore array to expose the surface of the conductive film under the nanopore array; And growing nanowires inside the nanopores of each of the nanopore arrays using the conductive film having the surface exposed. The above-described present invention deposits an aluminum thin film and an aluminum thin film through chemical mechanical polishing (CMP). By improving the surface roughness of the pores of the anodized aluminum formed by the subsequent anodization has the effect of improving the depth and size uniformity, and the present invention is also flat even when there is bending due to various patterns on the silicon substrate The fore-array of anodized aluminum can be implemented at a uniform depth, size and spacing.

Nanopore, AAO, Anodized, Nanowire, Trench, Conductive Film

Description

Manufacturing method of nano structure {METHOD FOR MANUFACTURING NANO STRUCTURE}

1A to 1D illustrate a method of forming a fore array of anodized aluminum oxide according to the prior art;

2a to 2c are SEM images showing a pore array of aluminum anodized after the secondary anodization process according to the prior art,

3A to 3D are cross-sectional views illustrating a method of manufacturing a fore array of anodized aluminum according to a first embodiment of the present invention;

4A to 4D are cross-sectional views illustrating a method of manufacturing a fore array of anodized aluminum according to a second embodiment of the present invention;

5A to 5D are cross-sectional views illustrating a method of manufacturing a fore array of anodized aluminum according to a third embodiment of the present invention;

6a to 6c are SEM photographs showing a pore array of aluminum anodization after the second anodization process according to the first embodiment of the present invention;

7A to 7E are SEM images showing a fore array of anodized aluminum in the case where a pattern is present on the substrate (particularly, the third embodiment);

8A to 8E are cross-sectional views illustrating a method of manufacturing a nanostructure using a pore array of anodized aluminum according to a fourth embodiment of the present invention;

9A to 9C are views for explaining a method of forming a trench in detail;

10A and 10B illustrate a nanowire growth method when the conductive film is titanium nitride.

* Explanation of symbols for the main parts of the drawings

31: Silicon Wafer

32: silicon oxide film

33: conductive film

34: aluminum thin film

The present invention relates to nanostructures, and more particularly, to a method of manufacturing nanostructures using a pore array of anodized aluminum oxide (AAO).

In general, nanostructured pores obtained from anodized aluminum oxide (AAO) have a constant pore position due to the action between the pores as the oxidation continues from the inlet of the initial randomly distributed pores. Has the property to transition to.

The initial distribution of the pores of the pore that occurs initially is because the formation of the pores is closely related to the roughness of the aluminum surface and thus the uneven distribution of the electric field. Growth characteristics also impair the regularity of the pores when there is a bend in the aluminum surface.

1A to 1D illustrate a method of forming a fore array of anodized aluminum oxide according to the prior art.

As shown in FIG. 1A, after the silicon oxide film 12 is formed on the silicon wafer 11, a conductive film 13 is formed on the silicon oxide film 12, and a sputtering method is performed on the conductive film 13. The aluminum thin film 14 is formed using various thin film formation techniques (including CVD and ALD), including (Sputter).

Subsequently, the silicon wafer 11 on which the aluminum thin film 14 is formed is immersed in the electrolyte solution. At this time, an aluminum thin film 14 is used as an anode in an electrolyte solution and a separate carbon electrode 15 is used as a cathode to flow a direct current.

In the method of immersing the aluminum thin film 14 in the electrolyte solution as described above, the electrolyte solution is any one of the acid electrolyte solution selected from oxalic acid, phosphoric acid or sulfuric acid.

As shown in FIG. 1B through the electrochemical oxidation in the electrolyte solution, the aluminum thin film 14 is oxidized to become alumina (Al ₂ O ₃ , 14a), and a plurality of regularly arranged inside the alumina 14a. Pores 14b are formed, and the surface of the aluminum thin film 14c whose thickness is reduced as the alumina 14a is formed has an uneven surface. The above oxidation process is called primary anodization.

Subsequently, as shown in FIG. 1C, the alumina 14a is immersed in an acid solution (phosphoric acid or a mixture of phosphoric acid and chromic acid), and then removed, and the aluminum thin film is immersed in an electrolyte solution as shown in FIG. 1A. The oxidation process of (14c) is performed.

As shown in FIG. 1D through the second oxidation process (secondary anodization), the aluminum thin film 14c is oxidized to become alumina (Al ₂ O ₃ , 14a), and a plurality of regularly arranged inside the alumina 14a. Pores 14b are formed, and the surface of the aluminum thin film 14d whose thickness is reduced as the alumina 14c is formed has an uneven surface.

As described above, a method of forming a plurality of pores by oxidizing an aluminum thin film at least twice in an electrolyte solution is called anodization.

However, the prior art has the following problems.

First, it is impossible to form a pore with a uniform size and depth due to poor surface flatness of the aluminum thin film.

That is, when the aluminum thin film is deposited using the sputtering method, the surface roughness of the surface of the aluminum thin film is very poor, and in this state, if the nano-sized pores are formed through anodization, the depth and size of the pores Uniformity becomes very uneven.

2A to 2C are SEM images showing the pore array after the secondary anodization process according to the prior art, and SEM images according to the time of the first anodization. 2A to 2C show primary anodization for 8 minutes, 30 minutes, and 60 minutes, respectively.

As shown in FIGS. 2A to 2C, it can be seen that even when anodization is performed, the surface roughness of the lower aluminum thin film is very rough, so that the depth and size uniformity of the pores formed after the anodization process are very poor.

This problem also occurs in many other materials besides aluminum thin films that can provide nano-sized pores through anodization.

Second, in the prior art, when using a pore array using anodization as a template (template) to grow nanowires such as carbon nanotubes inside the pore, alumina continuously present in the lower portion of the pore Impedes growth.

In particular, when the nanowires are grown using an electrochemical deposition method in which the conductive layer 13 at the lower part of the pore is exposed or a CVD method requiring a catalyst, the conductive layer 13 necessary for the nanowire growth is removed by removing continuous alumina at the lower part of the pore. There is a need to reveal, for this purpose the prior art etched alumina through wet etching.

However, such a wet etching method may not be used when the alumina thickness of the lower portion of the pore is similar to the thickness of the adjacent pore sidewalls because the entire pore is etched as well as the lower portion of the pore. Therefore, if the nanowires are to be grown inside the pore, there is a need for a technique capable of selectively removing continuous alumina under the pore.

The present invention has been proposed to solve the above problems of the prior art, and provides a method of manufacturing a nanostructure that can ensure the size and depth uniformity of nanopores formed when oxidizing an aluminum thin film through anodization. There is a purpose.

Method of manufacturing a nanostructure of the present invention for achieving the above object comprises the steps of forming a silicon oxide film on a silicon wafer; Selectively etching the silicon oxide layer to form a trench having a sidewall shape having a gentle curvature; Forming a conductive film on the silicon oxide film including the trench; Forming an aluminum thin film on which the nanopore array is to be formed on the conductive film; Planarizing the surface of the aluminum thin film through chemical mechanical polishing; Oxidizing the aluminum flattened surface through an anodization process to form alumina having nanopores; Further proceeding the anodization excessively to remove alumina under the nanopore array to expose the surface of the conductive film under the nanopore array; And growing nanowires inside the nanopores of each of the nanopores using the conductive layer exposed to the surface.

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Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. .

3A to 3D are cross-sectional views illustrating a method of manufacturing a nanostructure using a fore array of anodized aluminum according to a first embodiment of the present invention.

As shown in FIG. 3A, after the silicon oxide films SiO ₂ and 22 are formed on the silicon wafer 21, the conductive film 23 is formed on the silicon oxide film 22.

Subsequently, the aluminum thin film 24 is formed on the conductive film 23 using various thin film formation techniques (including CVD and ALD) including a sputtering method. Here, the silicon oxide film 22 may not be deposited.

As shown in FIG. 3B, the surface of the aluminum thin film 24 is planarized through chemical mechanical polishing (CMP).

By planarizing the surface of the aluminum thin film 24 through such chemical mechanical polishing, the surface roughness of the aluminum thin film 24 is improved. The symbol '24a' denotes a flattened aluminum thin film, and '24b' denotes an aluminum thin film removed through CMP.

The silicon wafer 21 having the flattened aluminum thin film 24a was immersed in the electrolyte solution (anodized), and the alumina was immersed in the acid solution to remove all of them, and then immersed in the electrolyte solution. Proceed. At this time, the aluminum thin film 24a is used as an anode in an electrolyte solution, and a separate carbon electrode (not shown) is used as a cathode to flow a direct current.

In the method of immersing the aluminum thin film 24a in the electrolyte solution as above, the electrolyte solution uses any one of an acid electrolyte solution selected from oxalic acid, phosphoric acid, or sulfuric acid.

When the anodization process is performed through the electrolysis in the electrolyte solution, as shown in FIG. 3c, the aluminum thin film 24a is oxidized to become alumina (Al ₂ O ₃ , 24c), and then inside the alumina 24c. A plurality of pores 24d are formed which are arranged regularly.

The first embodiment described above is a case where there is no pattern on the silicon wafer 21, and the CMP process of the aluminum thin film 24 is performed for 5 minutes using a silica-based slurry (pH = 7.2). On average, a thickness of 2 μm is polished. During the CMP process, the weight (or load) is 5 kg (three specimens of 2.5 cm x 2.5 cm at a time) and the rotation speed is 60 rpm.

As described above, after forming the plurality of pores (24d), the nanowires are grown inside the pore (24d), as shown in Figure 3d, anodizing process so that alumina (24c) does not exist below the pore (24d) When the excess anodization is further proceeded to expose the conductive film (23). That is, the excessive anodization process is further performed to completely remove the continuous alumina 24c under the pore to expose the conductive film 23. This uses the phenomenon that the dissolution and formation of the aluminum thin film grows in equilibrium during anodization at the lower portion of the pore, thereby consuming all of the aluminum thin film under the pore 24d.

In particular, in the case where the conductive film 23 is titanium nitride (TiN), even after all of the aluminum thin film is consumed, anodization is further performed to oxidize titanium nitride exposed under the pore 24d to titanium oxide, and titanium dioxide Can be selectively removed by wet etching to expose the underlying conductive titanium nitride.

In the case of growing the titanium oxide nanowires, the titanium oxide nanowires are grown by a method such as CVD without removing the titanium oxides generated during anodization, and as a seed of the titanium oxide nanowires to be grown later. You can.

On the other hand, in the case where the conductive film 23 exposed under the pore is a metal film that is difficult to oxidize, for example, platinum or gold, anodization is further progressed after all of the aluminum thin film is oxidized even without performing selective etching of the metal oxide. The conductive film 23 may be selectively exposed under the pore 24d. In this case, the conductive film 23 may be directly used as a catalyst for nanowire growth.

4A to 4D are cross-sectional views illustrating a method of manufacturing a nanostructure using a fore array of anodized aluminum according to a second embodiment of the present invention.

As shown in FIG. 4A, after the conductive film 33 is formed on the silicon wafer 31 on which surface curvature is generated by the silicon oxide film 32 having a predetermined pattern, the sputtering method is performed on the conductive film 33. The aluminum thin film 34 is formed using (Sputter). At this time, the surface 34a of the aluminum thin film 34 is uneven, and the pattern formed on the silicon oxide film 32 has recesses.

As shown in FIG. 4B, the surface 34a of the aluminum thin film 34 is planarized through chemical mechanical polishing (CMP). At this time, the chemical mechanical polishing process proceeds until the aluminum thin film 34b remains at a predetermined thickness.

By planarizing the surface of the aluminum thin film 34b through such chemical mechanical polishing, the surface roughness (roughness due to deposition and bending due to the structure of the lower pattern) of the aluminum thin film 34b is improved.

The silicon wafer 31 having the flattened aluminum thin film 34b is immersed in an electrolyte solution, immersed alumina in an acid solution, removed, and then immersed in the electrolyte solution, that is, at least two times of anodizing. . At this time, the aluminum thin film 33b is used as an anode in an electrolyte solution, and a separate carbon electrode (not shown) is used as a cathode to flow a direct current.

In the method of immersing the aluminum thin film 34b in the electrolyte solution as above, the electrolyte solution uses any one of an acid electrolyte solution selected from oxalic acid, phosphoric acid or sulfuric acid.

When the anodization process is performed through the electrolysis in the electrolyte solution, as shown in FIG. 4C, the aluminum thin film 34b is oxidized to become alumina (Al ₂ O ₃ , 35), and then into the alumina 35. A plurality of pores 36 are formed which are arranged regularly. In this case, the aluminum thin film 34b may have a reduced thickness, and thus a thin aluminum thin film 34c may remain, and the aluminum thin film 34c may be oxidized to form a plurality of pores 36 up to the inside of the recessed portion, or aluminum remaining in the recessed portion. After the etching of the alumina except for the second anodic oxidation process may be formed alumina having a plurality of pores arranged regularly only in the recess.

Thereafter, nanowires are grown in the pores 36, and as illustrated in FIG. 4D, excessive anodization is further performed during the anodization process so that the alumina 35 does not exist under the pores 36. ). That is, the excessive anodization process is further performed to completely remove the continuous alumina 35 under the pore to expose the conductive layer 33.

Particularly, in the case where the conductive film 33 is titanium nitride (TiN), after the aluminum thin film is exhausted, further anodization proceeds to oxidize the titanium nitride exposed under the pore 36 to titanium oxide, and titanium dioxide Can be selectively removed by wet etching to expose the underlying conductive titanium nitride.

On the other hand, in the case where the conductive film 33 exposed under the pore is a metal film that is difficult to oxidize, for example, platinum or gold, anodization is further progressed after all of the aluminum thin film is oxidized without performing selective etching of the metal oxide. The conductive film 33 may be selectively exposed under the pore 36, in which case the conductive film 33 may be used directly as a catalyst for nanowire growth.

5A to 5D are cross-sectional views illustrating a method of manufacturing a nanostructure using a fore array of anodized aluminum according to a third embodiment of the present invention.

As shown in FIG. 5A, after the conductive film 43 is formed on the silicon wafer 41 where surface bending occurs by the silicon oxide film 42 having a predetermined pattern, a sputtering method is performed on the conductive film 43. The aluminum thin film 44 is formed using (Sputter). At this time, the surface 44a of the aluminum thin film 44 is uneven, and the pattern formed on the silicon oxide film 42 has recesses.

As shown in FIG. 5B, the surface 44a of the aluminum thin film 44 is planarized through chemical mechanical polishing (CMP). At this time, the chemical mechanical polishing process proceeds until it remains inside the pattern of the silicon oxide film 42 formed on the silicon wafer 41.

By chemically polishing the surface of the aluminum thin film 44, the surface roughness of the aluminum thin film 44 is improved.

The silicon wafer 41 having the flattened aluminum thin film 44b is immersed in an electrolyte solution, immersed alumina in an acid solution, removed, and then immersed again in the electrolyte solution. At this time, the aluminum thin film 44b is used as an anode in an electrolyte solution, and a direct current flows with a separate carbon electrode (not shown) as a cathode.

In the method of immersing the aluminum thin film 44b in the electrolyte solution as above, the electrolyte solution uses any one of an acid electrolyte solution selected from oxalic acid, phosphoric acid or sulfuric acid.

When the anodization process is performed through the electrolyte solution, as shown in FIG. 5C, the aluminum thin film 44b is oxidized to be alumina (Al ₂ O ₃ , 45), and is regularly arranged inside the alumina 45. Multiple pores 46 are formed. At this time, the thickness of the aluminum thin film 44b is reduced, so that the thin aluminum thin film 44c remains.

As described above, after forming the plurality of pores 46, the nanowires are grown inside the pore 46, as shown in Figure 5d, anodizing process so that the alumina 45 does not exist below the pore 46 When the excess anodization is further proceeded to expose the conductive film 43. That is, the excessive anodization process is further performed to completely remove the continuous alumina 45 under the pore to expose the conductive layer 43. This uses the phenomenon that the dissolution and formation of the aluminum thin film grows in equilibrium during anodization at the lower part of the pore, thereby consuming all the aluminum thin film under the pore 45.

In particular, in the case where the conductive film 43 is titanium nitride (TiN), anodization is further performed after the aluminum thin film is exhausted to oxidize the titanium nitride exposed under the pore 46 to titanium oxide, and titanium dioxide Can be selectively removed by wet etching to expose the underlying conductive titanium nitride.

On the other hand, in the case where the conductive film 43 exposed under the pore is a metal film that is difficult to oxidize, for example, platinum or gold, anodization is further progressed after all of the aluminum thin film is oxidized without performing selective etching of the metal oxide. The conductive film 43 may be selectively exposed under the pore 46, in which case the conductive film 43 may be used directly as a catalyst for nanowire growth.

6A to 6C are SEM photographs showing a pore array of aluminum anodization after the second anodization process according to the first embodiment of the present invention, and SEM images according to the time of the first anodization. 6A to 6C show primary anodization for 8 minutes, 30 minutes, and 60 minutes, respectively.

6a to 6c, it can be seen that the surface roughness of the lower aluminum thin film to be anodized is improved (that is, the surface is smooth and smooth) to improve the depth and size uniformity of the pores formed after the anodizing process. Can be.

7A to 7E are SEM images showing a fore array of anodized aluminum in the case where a pattern is present on a silicon wafer (particularly, the third embodiment). Here, the fore-array is formed only on the recess, and the pattern is formed to have a width of several to several hundred micrometers of 2 μm-thick SiO ₂ coated by CVD through photolithography and dry etching.

FIG. 7A is a photograph showing that the surface is flattened after CMP is formed in the order of a hard pad and a soft pad in a state in which aluminum is formed to a thickness of 8 μm and a load of 3 kg is given.

As such, when the pattern is present, the substrate flatness may be improved by using the hard pad and the soft pad at a lower load. If there is a pattern, the time of the CMP process proceeds for a few minutes (2 to 3 minutes).

7B is a photograph after anodization of the aluminum thin film planarized through CMP until only the aluminum film of the pattern recess remains. TiN (50 nm) and Ti (50 nm) are used as the conductive layer under the aluminum. That is, the order is Al / TiN / Ti / SiO ₂ / Si.

FIG. 7C is a planar view of an example in which the pore array is formed only in the recess by anodizing aluminum in the recess after removing the already formed alumina. For reference, the white spots outside the rectangles are not pores, but TiO dots made by oxidizing the underlying TiN.

FIG. 7D is a cross-sectional photograph of an example in which an aluminum oxide in the recess is anodized after removing the already formed alumina to form a pore array only in the recess (FIG. 7C). Less anodization at the edges leads to the discovery of the remaining aluminum.

FIG. 7E is a cross-sectional photograph of a pore array formed in a wider pattern than FIG. 7D.

8A to 8E are cross-sectional views illustrating a method of manufacturing a nanostructure using a fore array of anodized aluminum according to a fourth embodiment of the present invention.

As shown in FIG. 8A, after the silicon oxide film 52 is formed on the silicon wafer 51, the trench 53 is formed by selectively etching the silicon oxide film 52. At this time, the etching process for forming the trench 53 is performed in parallel with the wet etching or dry etching and the wet etching in order to show the isotropic etching characteristics of the sidewalls of the trench 53. When the trench 53 is formed through the wet etching, the sidewalls of the trench 53 have a gentle curvature, and the sidewalls of the gentle curvature have a gentle curvature, thereby reducing the ratio of holding the side of the pore during the subsequent anodization process. In addition to reducing the additional stress, it also prevents the aluminum film from remaining unoxidized. In addition, when the sidewall of the trench 53 is smoothed, the problem of bending the pores to the sidewall may be solved. In addition, if the depth of the trench 53 is reduced, anodization may be terminated before the phenomenon in which the growth of the pores is suppressed appears.

As a result, the reason why the sidewall shape of the trench 53 has a gentle curvature is to allow the pore array to be uniformly formed inside the trench 53.

9A to 9C are diagrams for describing a method of forming a trench in detail.

As shown in FIG. 9A, after the photoresist pattern PR is formed on the silicon wafer 51 on which the silicon oxide film 52 is present, the photoresist pattern PR is formed, and then wet etching is performed using the photoresist pattern PR. The silicon oxide film 52 is etched to form the trench 53 having a gentle slope of the sidewall.

9B and 9C illustrate a trench forming method for applying when the inclination of the trench sidewall of FIG. 9A is too slow. The silicon oxide film 52 may be dry etched in advance, and the first trench 53A may be formed. After forming (FIG. 9B), the slope of the sidewall of the trench 53 that is finally formed when wet etching is performed in FIG. 9C is reduced.

After forming the trench 53 having a smooth curvature of the side wall as described above, as shown in FIG. 8B, the conductive film 54 is formed on the silicon oxide film 52 having the trench 53 formed thereon, and then conductive. The aluminum thin film 55 is formed on the film-forming 54 using the sputtering method. At this time, the surface 55a of the aluminum thin film 55 is bumpy.

As shown in FIG. 8C, the surface 55a of the aluminum thin film 55 is planarized through chemical mechanical polishing (CMP). At this time, the chemical mechanical polishing process proceeds until it remains inside the pattern of the silicon oxide film 52 formed on the silicon wafer 51.

By planarizing the surface of the aluminum thin film 55 through such chemical mechanical polishing, the surface roughness of the aluminum thin film 55 is improved.

The silicon wafer 51 having the flattened aluminum thin film 55b is immersed in an electrolyte solution, immersed alumina in an acid solution, removed, and then immersed again in the electrolyte solution. At this time, the aluminum thin film 55b is used as an anode in an electrolyte solution, and a direct current flows with a separate carbon electrode (not shown) as a cathode.

In the method of immersing the aluminum thin film 55b in the electrolyte solution as above, the electrolyte solution uses any one of an acid electrolyte solution selected from oxalic acid, phosphoric acid, or sulfuric acid.

When the anodization process is performed through the electrolysis in the electrolyte solution, as shown in FIG. 8D, the aluminum thin film 55b is oxidized to become alumina (Al ₂ O ₃ , 56), and thus inside the alumina 56. A plurality of pores 57 are formed which are arranged regularly.

As described above, after forming the plurality of pores 57, as shown in Figure 8e, to grow the nanowires 58 inside the pore 57, there is no alumina 56 under the pore 57 In order to prevent excessive anodization during the anodization process in FIG. 8D, the conductive layer 54 is exposed. That is, the excessive anodization process is further performed to completely remove the continuous alumina 56 under the pore to expose the conductive film 54. This uses the phenomenon that the dissolution and formation of the aluminum thin film grows in equilibrium during anodization at the lower portion of the pore, thereby consuming all of the aluminum thin film under the pore 57.

In particular, when the conductive film 54 is titanium nitride (TiN), it will be described with reference to FIGS. 10A and 10B.

As shown in Figs. 10A and 10B, even after the aluminum thin film is exhausted, further anodization proceeds to oxidize the titanium nitride exposed under the pore 57 to titanium oxide 54a (see Fig. 10A). After the titanium oxide 54a was selectively removed through wet etching, a catalyst or a seed was deposited through electro-deposition using an exposed conductive film (titanium nitride), followed by nanowires 58. Grow (see FIG. 10B).

In the case where the nanowires 58 are grown with titanium oxide, the titanium oxide nanoparticles are removed by a method such as CVD without removing the titanium oxide 54a and using as a seed of the titanium oxide nanowires to be grown later. The wire can be grown.

On the other hand, in the case where the conductive film 54 exposed under the pore is a metal film that is difficult to oxidize, for example, platinum or gold, anodization is further progressed after all of the aluminum thin film is oxidized even without performing selective etching of the metal oxide. The conductive film 54 may be selectively exposed under the pore 57, in which case the conductive film 54 may be used directly as a catalyst for nanowire growth.

In the above-described fourth embodiment, the pattern formed in the silicon oxide film 52, that is, the sidewalls of the trench 53 have a gentle curvature, so that the trench 53 in the anodizing process of the aluminum thin film 55 is formed. It is possible to prevent the non-uniformity of the pores in the side wall to form a uniform fore as a whole.

That is, if the sidewalls of the trench 53 have a gentle curvature, the ratio of holding the side of the pores during the anodization process can be reduced, thereby reducing additional stress and preventing the aluminum thin film remaining without oxidation. . In addition, when the sidewall of the trench 53 is smoothed, the problem of bending the pores to the sidewall can also be solved. In addition, if the depth of the trench 53 is reduced, anodization may be terminated before the phenomenon in which pore growth is suppressed appears.

In the present invention described above, in order to directly anodize the aluminum thin film deposited on the silicon wafer and obtain a nano-pore structure, the thickness of the thin film must be sufficiently thick so that it can withstand a long oxidation time, and the aluminum thin film is sufficiently flattened to nanopore. Inhomogeneities in the creation of inlets should be minimized. In addition, in the application of the nanopore structure of anodized aluminum oxide to the actual silicon wafer, it is necessary to minimize the influence of the surface bending caused by the pattern formed on the silicon wafer. In order to selectively place the nanopore structure of anodized aluminum on the silicon wafer, the channel structure may be formed only in well-defined trench portions through the silicon wafer patterning process, in which case the current in the trench may not be adequately interrupted by the aluminum in the trench. A conductive film may be inserted to induce flow. In particular, the titanium or titanium nitride film used as an adhesive layer in the process of depositing aluminum has good conductivity, and thus may be used as the aforementioned conductive film. In addition, by inserting a layer that can be used as a catalyst in the conductive film may help the growth of nanowires after pore growth.

In the above embodiments, instead of silicon wafers, glass (ie, silica (SiO ₂ ) or other glass), plastic substrates such as sapphire, quartz substrates and metal substrates, ceramic substrates, as well as other semiconductors It will be appreciated that the substrate is not limited to, for example, gallium arsenide and silicon carbide. In addition, nanopore arrays can be formed in suitable materials that can be oxidized, such as by anodic oxidation, to form them. For example, instead of aluminum, other metals, for example titanium (forming a titanium oxide film in anodization), tantalum (forming Ta ₂ O ₅ in anodization), niobium or alloys thereof Can be used. In general, any metal or semiconductor that can be oxidized to form a microporous structure can be used.

Then, after the nanowires are grown, the surface area of the nanowires can be increased by exposing the nanowires to the outside by removing the alumina in which the nanopores are formed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

The present invention described above has the effect of improving the depth and size uniformity of pores of anodized aluminum formed by subsequent anodization by depositing an aluminum thin film and improving the surface roughness of the aluminum thin film through chemical mechanical polishing (CMP). have.

In addition, the present invention has the effect that even in the case of bending due to the various patterns on the silicon substrate can be implemented in a uniform depth, size and spacing of the anodized aluminum anodized.

In addition, the present invention by removing the alumina formed at the end of the forelay of the anodized aluminum by using the oxidation effect and the chemical etching method of the conductive film deposited on the bottom of the aluminum to expose the lower portion of the forelay to a suitable conductive film, such conductivity The membrane can be used to selectively grow nanowires in a fore array.

In addition, the present invention by depositing a variety of nanowires, including carbon nanotubes in a plurality of nanometer-sized forear formed on the anodized aluminum (alumina) frame, it is effective to make a variety of nano-sensors using such nanowires have.

Claims

Forming a silicon oxide film on the silicon wafer;

Selectively etching the silicon oxide layer to form a trench having a sidewall shape having a gentle curvature;

Forming a conductive film on the silicon oxide film including the trench;

Forming an aluminum thin film on which the nanopore array is to be formed on the conductive film;

Planarizing the surface of the aluminum thin film through chemical mechanical polishing;

Oxidizing the aluminum flattened surface through an anodization process to form alumina having nano-pores;

Further proceeding the anodization excessively to remove alumina under the nanopore array to expose the surface of the conductive film under the nanopore array; And

Growing nanowires inside each of the nanopores using the conductive layer exposed to the surface;

Method of producing a nanostructure comprising a.

The method of claim 1,

The chemical mechanical polishing,

Method of producing a nanostructure, characterized in that the progress until the aluminum thin film remains only in the trench.

The method of claim 1,

Forming the trench,

Method of producing a nanostructure, characterized in that the wet etching.

The method of claim 3,

Method of producing a nanostructure, characterized in that for performing the dry etching prior to the wet etching in order to adjust the slope of the sidewall of the trench.

The method of claim 1,

The conductive film is a method of manufacturing a nanostructure, characterized in that formed with a material that is simultaneously oxidized during the anodization process.

The method of claim 5,

The conductive film is a method of manufacturing a nanostructure, characterized in that formed of titanium nitride.

The method of claim 1,

The conductive film is a method of manufacturing a nanostructure, characterized in that formed with a material that does not proceed oxidation during the anodization process.

The method of claim 7, wherein

The conductive film is a method of manufacturing a nanostructure, characterized in that formed of platinum or gold.

The method of claim 1,

And oxidizing the conductive film to an oxide when the excessive anodization, and the oxide is used as a seed during the growth of the nanowires.

10. The method of claim 9,

The conductive film is titanium nitride, and the oxide and nanowires are titanium oxide manufacturing method, characterized in that the titanium oxide.

The method of claim 1,

The chemical mechanical polishing,

The planar surface curvature by the trench while the planarization of the nanostructures, characterized in that the progress until the aluminum thin film remaining on the silicon oxide film to a predetermined thickness.

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