JP2008150674A - Method for producing fine structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily producing a fine structure having pores in a nanometer scale. <P>SOLUTION: The method for producing a fine structure comprises: a stage where a projecting part in an electrode is brought into contact with the layer to be subjected to anode oxidation, thereafter, voltage is applied, and an oxidized region is formed in the contact part with the projecting part of the electrode in the layer to be subjected to anode oxidation; a stage where the layer to be subjected to anode oxidation with the oxidized region formed is subjected to anode oxidation, so as to form first pores in the oxidized region; and a stage where the layer to be subjected to anode oxidation is subjected to anode oxidation once more, so as to form second pores different from the first pores in the region other than the oxidized region. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a microstructure having a concavo-convex structure having nanometer-scale pores using partial oxidation and anodization.

  As techniques for producing a fine structure on the surface of an object, techniques such as photolithography, electron beam exposure, X-ray exposure, and nanoimprint lithography are known. In recent years, nanoelectrode lithography has been proposed in Non-Patent Documents 1 and 2.

As a method other than the above, a method for producing a fine structure by a bottom-up method using an anodic oxidation method of aluminum or a molecular self-organization structure is known. In the anodic oxidation method of aluminum or the like, if a regular concave structure is formed on the surface of the anodized layer in advance, a hole structure can be formed starting from the concave structure. (See Patent Document 1)
JP-A-10-121292 Jpn. J. et al. Appl. Phys. , 42, L92 (2003) Jpn. J. et al. Appl. Phys. , 44, p. 1119 (2005)

  By the way, in the direct drawing technique such as the electron beam drawing or the ion beam drawing described above, it takes a long time to form a pattern as the structure becomes finer. Therefore, for products that are mass-produced inexpensively, masks for X-rays, ultraviolet exposure, and imprint molds are precisely manufactured using direct drawing technology, etc., and in a short time collectively by photolithography and nanoimprint lithography. The technique of patterning is the mainstream.

  However, the size of the fine structure that can be formed by any of these methods is limited. At present, even in electron beam exposure that can produce the finest structure, a single dot of φ10 nm can be formed, but it is difficult to arrange this in a large area with a pitch of 20 nm or less.

  In addition, the conventional self-organization method using anodic oxidation described above and the bottom-up method using a molecular self-organization structure are suitable for forming a large area. In order to form a structure including the same on one substrate, a complicated process is required. For example, in the method of forming a concave structure as a regularly arranged starting point and performing anodization to form a regularly arranged hole structure in the concave structure portion, the concave structure of the starting point is not formed. A random pore structure is formed in the region. Therefore, in order to form an array structure of several types on one substrate, masking and peeling by photolithography or the like must be repeated.

  The present invention has been made in view of such a background art, and a microstructure having nanometer-scale pores can be easily obtained by using a conventional anodic oxidation method such as aluminum and a technology of a nanoelectrode lithography method. The method of manufacturing is provided.

  In the manufacturing method of the fine structure that solves the above-mentioned problem, after the convex part of the electrode having the convex part is brought into contact with the anodized layer, a voltage is applied to the contact part of the convex part of the electrode in the anodized layer. The method includes a step of forming an oxidized region and a step of anodizing the anodized layer in which the oxidized region is formed to form a hole in the oxidized region.

  In addition, in the method for manufacturing a microstructure that solves the above-described problem, after the convex portion of the electrode having a convex portion is brought into contact with the anodized layer, a voltage is applied to contact the convex portion of the electrode in the anodized layer. A step of forming an oxidized region in a portion; a step of anodizing the anodized layer in which the oxidized region is formed to form a first hole in the oxidized region; It has the process of forming the 2nd hole different from a 1st hole in area | regions other than an oxidation area | region.

It is preferable that a hole starting point for forming a hole is provided in the anodized layer.
It is preferable that the convex portion of the electrode is brought into contact with the anodized layer via a semiconductor layer or an insulator layer.

The anodized layer is preferably made of aluminum or an aluminum alloy.
It is preferable to form the second hole after filling the first hole with the inclusion.

ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing easily the microstructure which has a nanometer scale hole can be provided.
In addition, the present invention can provide a method for easily manufacturing a microstructure having holes of different sizes.

Hereinafter, the present invention will be described in detail.
In the fine structure manufacturing method of the present invention, after the convex part of the electrode having the convex part is brought into contact with the anodized layer, a voltage is applied to form an oxidized region in the contact part of the convex part of the electrode in the anodized layer. A step of forming, a step of anodizing the anodized layer in which the oxidized region is formed to form a first hole in the oxidized region, a region other than the oxidized region by anodizing the anodized layer again And a step of forming a second hole different from the first hole.

A nanometer scale represents having a scale of less than 1 μm.
The first method of the present invention will be described with reference to FIGS. FIG. 1 is a process diagram showing one embodiment of the method for producing a microstructure of the present invention. FIG. 2 is a plan view showing one embodiment of the fine structure obtained by the manufacturing method of the present invention.

  First, the electrode 1 having the convex portions 15 as shown in FIG. 1A is formed of a metal such as Ni. The anodized layer 3 is formed on the substrate 4, the anodized layer 3 and the electrode 1 are opposed, and only the electrode convex region 2 is in contact with the surface of the anodized layer 3. Here, the anodized layer 3 is preferably made of aluminum or an aluminum alloy, for example.

  When a voltage is applied with the anodized layer 3 as an anode in this contacted state, the surrounding oxygen atoms and the anodized layer are combined, and the oxidized region 6 by the electrode is in contact with the projecting portion of the electrode in the anodized layer. Is formed (FIG. 1B). The formation rate of this oxidized region depends on the ambient temperature, humidity, oxygen concentration, and the like. In the case where oxidation does not proceed due to excessive current flowing through the anodized layer, a resistance layer may be provided on the surface with a semiconductor layer or an insulator layer interposed therebetween. The thickness of the resistance layer must be changed in accordance with the resistance value. However, the thicker the film is, the farther from the anodized layer, the wider the area oxidized on the surface of the anodized layer. Further, since the oxidized region proceeds isotropically, the thickness of the anodized layer is preferably approximately the same as the width of the convex portion of the electrode.

As the semiconductor layer or insulator layer of the resistance layer, for example, a water-soluble resin, a resin soluble in an organic solvent, or the like is preferable.
Next, when the electrode 1 is removed and the anodized layer 3 is immersed in an acidic solution using an anode and an anodic oxidation voltage is applied, a hole is formed in the oxidized region 6 (first anodic oxidation). In general, in the anodic oxidation of aluminum, the following relationship is established, and the interval between the formed holes can be controlled by an applied voltage.

  When a voltage is applied, oxidation proceeds from the surface of aluminum, and when an oxide layer having a certain thickness depending on the voltage is reached, holes are formed from the surface by an etching reaction. Along with the formation of the holes, the oxidation reaction further proceeds in the film thickness direction.

  When the first anodic oxidation is performed on the anodized layer in which the oxidized region 6 is formed by the electrodes as shown in FIG. 1B, the formation of holes starts in the oxidized region 6 by the electrodes before the non-oxidized region 10. . Therefore, when the thickness (D) of the anodized layer 3 is smaller than the hole interval (L), the first anodic oxidation hole formation in the oxidized portion 7 of the non-oxidized region 10 starts before the first The bottom of the hole 8 due to the anodic oxidation reaches the substrate and the hole formation is completed (FIG. 1C). The thickness (D) and the hole interval (L) of the anodized layer 3 are preferably D / T = 0.5 to 2.

  Next, the second anodic oxidation is performed under a condition different from the first anodic oxidation condition (second anodic oxidation). Since the holes formed by the first anodic oxidation have already reached the substrate, the formation of the holes does not proceed, and the holes 9 formed by the second anodic oxidation are formed in the non-oxidized region 10. Since the first and second anodic oxidation conditions are different, the size of the hole 8 is different between the hole 8 by the first anodic oxidation and the hole 9 by the second anodic oxidation.

  Here, if a layer is provided between the substrate 4 and the anodized layer 3 so as to be resistant to anodization and the bottom of the hole 8 formed by the first anodization is not electrically connected to the substrate during the second anodization. good. For example, titanium, niobium, tungsten and the like are preferable. When the holes 9 by the second anodic oxidation reach the substrate, as shown in FIG. 1D and FIG. 2, holes with different intervals can be formed in adjacent regions.

  Here, when the conditions of the second anodic oxidation are greatly different from those of the first anodic oxidation, it is difficult to realize the first method of the present invention. This is because when the hole interval formed under the second anodizing condition is about ½ or less of the hole interval formed under the first anodizing condition, the first anodizing is performed. Further holes may be formed between the holes due to anodic oxidation. Moreover, this may depend not only on the pore spacing but also on conditions such as an anodizing bath.

  Next, the 2nd method of this invention is demonstrated using FIG. 3 and FIG. FIG. 3 is a process diagram showing another embodiment of the method for producing a microstructure of the present invention. FIG. 4 is a plan view showing another embodiment of the fine structure obtained by the manufacturing method of the present invention.

  This is an example of a case where holes are equal in distance but different in diameter and are regularized. Similar to the first method of the present invention, the anodized layer 3 is provided on the substrate 4. Next, hole start points 11 for ordering are formed on the surface of the anodized layer 3. The formation method may be an FIB method (Focused Ion Beam Method) or a combination of general photolithography and etching methods (FIG. 3A).

  Similar to the first method, the electrode convex region 2 is brought into contact with each other to form the oxidized portion 5 by the electrode (FIG. 3B), and the first anodic oxidation is performed. A first anodizing hole 8 is formed in the oxidized region 6 by the electrode, and the first anodizing is stopped in a state where the hole reaches the substrate and no hole is formed in the non-oxidized region 10 by the electrode ( FIG. 3 (c)). This state can be easily obtained by adjusting the anodizing conditions and the film thickness of the anodized layer. FIG. 3 shows an example in which the first anodic oxidation is performed under the condition that the width of the hole region 6 by the electrode is substantially equal to the hole interval.

  Next, the substrate is immersed in a phosphoric acid aqueous solution and etched to widen the hole diameter to an arbitrary size. Then, anodic oxidation is performed again under the same conditions as the first anodic oxidation (second anodic oxidation), and holes are formed in the non-oxidized region 10 by the electrodes (FIG. 3E). If necessary, the hole diameter is increased again. Since the holes are formed from the starting points, for example, if the starting points 10 are arranged in a triangular lattice shape as shown in FIG. 4A, the hole structure has the distribution shown in the plan view as shown in FIG. Become.

  Here, when the anodized layer is thick, holes are formed in the non-oxidized region 10 by the electrodes before the holes 8 by the first anodization reach the substrate by the first anodization. End up. In such a case, if the first anodic oxidation is stopped immediately before the hole is formed in the non-oxidized region by the electrode and the second anodic oxidation is performed after performing some treatment, the hole due to the first anodic oxidation becomes It will grow even deeper.

  As described above, when the method of the present invention is used, holes having different intervals and hole diameters can be formed in adjacent regions on one substrate without performing complicated photolithography and etching.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Example 1
1 and 2 show an embodiment where the oxidized region is wide, random and the hole pitch is different.

  The electrode 1 is a nickel (Ni) thin plate having a surface structure in which line-shaped convex structures having a width of 200 nm are arranged at intervals of 400 nm. On the silicon (Si) substrate 4, titanium (Ti) 10 nm is laminated, aluminum (Al) is laminated 75 nm as the anodized layer 3, and a water-soluble resin material is applied 15 nm as a resistance layer. Next, the electrode 1 is brought into contact with the resistance layer, and a voltage having a strength corresponding to the resistance of the resistance layer is applied to oxidize Al in the electrode convex region (FIGS. 1A and 1B).

  The electrode is removed, the substrate is immersed in an aqueous sulfuric acid solution (1 mol / L, 3 ° C.) using the anode, and a voltage of 20 V is applied to perform the first anodic oxidation. The water-soluble resin layer on the surface is dissolved by being immersed in the aqueous solution. Holes randomly arranged with an average interval of 50 nm are formed in the oxidized region 6 by the electrode, and voltage application is stopped when the bottom of the hole reaches the substrate (FIG. 1 (c)). At this time, the oxidized portion 7 by anodic oxidation is formed in the non-oxidized region 10 by the electrode, and no hole is formed yet. Next, the substrate is immersed in an oxalic acid aqueous solution (0.3 mol / L, 16 ° C.) as an anode, and a voltage of 40 V is applied to perform second anodic oxidation. Randomly arranged holes with an average interval of 100 nm are formed in the non-oxidized region 10 by the electrodes (FIGS. 1D and 2). A new hole is not formed in the oxidized region 6 by the electrode due to the second anodic oxidation condition.

Thereby, it is possible to obtain a pore structure composed of pores having pore diameters of 10 nm and 20 nm in which regions having a small interval and large regions are alternately arranged in a line.
Example 2
FIG. 3 and FIG. 4 show an embodiment in the case where the oxidation region is one row, regular and has different hole diameters.

  An Ni thin plate having a line-shaped convex structure with a width of 100 nm on the surface is defined as an electrode 1. On the Si substrate 4, Ti is laminated with a thickness of 10 nm, and as the anodized layer 3, Al is laminated with a thickness of 75 nm. Beams are irradiated onto the Al surface by the FIB method to form hole start points with a depth of about 1 nm to 10 nm and an interval of 100 nm arranged in a triangular lattice pattern (FIG. 4A). The starting point depth need not be precise.

  A water-soluble resin material having a thickness of 10 nm is applied thereon as a resistance layer. The electrode 1 is brought into contact with the resistance layer, and a voltage is applied to oxidize Al in the electrode convex region (FIG. 3A). At this time, the position of the hole start point 11 and the center of the convex structure of the electrode are matched as shown in FIGS. 4 (a) and 3 (b). The electrode is removed, the substrate is immersed in an oxalic acid aqueous solution (0.3 mol / L, 16 ° C.) using the anode, and a voltage of 40 V is applied to perform the first anodic oxidation. In the oxidized region 6 by the electrode, holes are regularly formed at the position of the hole start point and reach the substrate, and an oxidized portion 7 by anodic oxidation is formed in the non-oxidized region by the electrode (FIG. 3C). . This is immersed in a phosphoric acid aqueous solution (0.3 mol / L, 25 ° C.) for 60 minutes to enlarge the pore size.

  Next, again using the substrate as the anode, the substrate is immersed in an oxalic acid aqueous solution (0.3 mol / L, 16 ° C.) that is the same as the first anodic oxidation condition, and a voltage of 40 V is applied to perform the second anodic oxidation. The hole 9 by the second anodic oxidation is formed from the hole start point (FIG. 3 (e), FIG. 4 (b)).

  As a result, one row with a large pore diameter of 80 nm can be formed in the pores with a pore diameter of 20 nm regularly arranged at a pitch of 100 nm. Here, when the second anodic oxidation is performed after filling the hole made by the first anodic oxidation with a resin made of a material that is not affected by the second anodic oxidation, the inclusions are included only in some of the holes. Structure can be obtained. Such a structure can be used for various applications such as biochips and photonic crystals.

Example 3
An example in which the first and second embodiments of the present invention are combined will be described with reference to FIG.
A hole start point is formed on the Al surface of the substrate similar to that in Example 2. Two types of rectangular lattice arrays are adjacent to each other at the hole start point. In the first region 13, the short side interval of the unit cell is 100 nm, the long side interval is 150 nm, and the second region 14 is short of the unit cell. The side interval is 150 nm and the long side interval is 225 nm. The second area is an array in which three columns are inserted in a part of the first area in the short side direction.

  An Ni thin plate having a line-shaped convex structure with a width of 430 nm on the surface is used as the electrode 1, is brought into contact with the resistance layer, and a voltage is applied to oxidize Al in the peripheral portion of the electrode convex region. Next, the substrate is immersed in a phosphoric acid aqueous solution (0.3 mol / L, 10 ° C.) as an anode, and a voltage of 60 V is applied to perform first anodic oxidation. It stops when a hole is formed in the oxidized region 6 by the electrode and reaches the substrate. This is immersed in a phosphoric acid aqueous solution (0.3 mol / L, 25 ° C.) and etched until the pore diameter reaches 50% of the pore spacing. Next, the substrate is immersed in a mixed acid aqueous solution (20 ° C.) in which a phosphoric acid aqueous solution (0.3 mol / L) and an oxalic acid aqueous solution (0.3 mol / L) are mixed at a ratio of 1: 1, and a voltage of 40 V is set using the substrate as an anode. Is applied to perform second anodic oxidation. Next, it is immersed again in a phosphoric acid aqueous solution (0.3 mol / L, 25 ° C.), and etching is performed until the hole diameter of the second region reaches 50% of the hole interval. At this time, the holes in the first region are further etched.

  The holes have a rectangular shape similar to the aspect ratio of the hole interval, and a plan view of the manufactured structure is as shown in FIG. Such a structure can be used for a magnetic recording medium.

  Since the present invention can provide a method for easily producing a microstructure having nanometer-scale pores, it can be used for patterned media, photonic crystals, biochips, and the like.

It is process drawing which shows one embodiment of the manufacturing method of the microstructure of this invention. It is a top view which shows one embodiment of the fine structure obtained by the manufacturing method of this invention. It is process drawing which shows the other embodiment of the manufacturing method of the microstructure of this invention. It is a top view which shows the other embodiment of the fine structure obtained by the manufacturing method of this invention. It is a top view which shows the other embodiment of the fine structure obtained by the manufacturing method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode 2 Electrode convex area | region 3 Anodized layer 4 Substrate 5 Oxidation part by electrode 6 Oxidation area | region by electrode 7 Oxidation part by anodization 8 Hole by 1st anodic oxidation 9 Hole by 2nd anodic oxidation 10 Non-oxidation by electrode Region 11 Hole start point 12 Hole spacing 13 First region 14 Second region 15 Projection

Claims (6)

  Forming an oxidized region at a contact portion of the projecting portion of the electrode in the anodized layer by applying a voltage after contacting the projecting portion of the electrode having the projecting portion with the anodized layer; and forming the oxidized region A method for producing a microstructure, comprising the step of anodizing the formed anodized layer to form a hole in the oxidized region.   Forming an oxidized region at a contact portion of the projecting portion of the electrode in the anodized layer by applying a voltage after contacting the projecting portion of the electrode having the projecting portion with the anodized layer; and forming the oxidized region A step of anodizing the formed anodized layer to form a first hole in the oxidized region; a second step different from the first hole in a region other than the oxidized region by anodizing the anodized layer again A method for producing a microstructure, comprising the step of forming a hole.   The method for producing a microstructure according to claim 1 or 2, wherein a hole starting point for forming a hole is provided in the anodized layer.   The method for producing a microstructure according to any one of claims 1 to 3, wherein the convex portion of the electrode is brought into contact with the anodized layer via a semiconductor layer or an insulator layer.   The method for manufacturing a microstructure according to any one of claims 1 to 4, wherein the anodized layer is made of aluminum or an aluminum alloy.   The method for producing a microstructure according to claim 2, wherein the second hole is formed after filling the first hole with the inclusion.

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