JP3848303B2 - Structure, functional structure, and method of manufacturing magnetic recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a structure having holes. In particular, the present invention relates to a method of manufacturing a functional structure such as a magnetic recording medium by filling a hole with a functional material such as a magnetic material.
[0002]
[Prior art]
As a technology for creating a fine structure on the surface of an object, a nanoimprint (not a conventional lithography using light or electron beams) is used to form a nanometer-sized structure by directly pressing an uneven structure onto a workpiece. A method called nano-imprint has been proposed as a new technique (US Pat. No. 5,772,905).
[0003]
In this method, as shown in FIG. 9, a stamper 100 having a convex structure pattern 103 with a size of several tens to several hundreds of nanometers processed by an electron beam or the like is pressed against a resin thin film 104 formed on a flat substrate 105. By forming the concavo-convex structure pattern by pulling apart, the concave portion (mold region) 106 of the resin thin film is removed by reactive ion etching or the like, and the substrate 105 is etched using this resin layer as a mask, so The nanometer-sized structures 107 and 108 having the above are formed. In this method, in order to prevent the stamper 100 from deteriorating due to the pressing, the pressing is stopped before the convex structure 103 of the stamper 100 reaches the substrate 105 on which the resin thin film 104 is formed, and the stamper 100 is pulled apart. In this method, even when the pressing is stopped immediately before the convex structure surface of the stamper reaches the resin thin film, the resin thin film may come into contact with the concave structure surface of the stamper due to the swelling of the resin due to the pressing.
[0004]
Such contact may cause irregularities in the uneven shape formed on the resin thin film when the stamper is pulled away from the resin thin film.
[0005]
[Problems to be solved by the invention]
Then, the subject of this invention is providing the structure which formed the hole in the desired position.
[0006]
[Means for Solving the Problems]
The present invention is a method for producing a structure having holes, and a first member having a pattern forming layer made of a material that is dissolved by an anodic oxidation treatment is prepared on an anodized film, and a plurality of protrusions are provided. The second member is pressed against the pattern forming layer to form a concavo-convex structure in the pattern forming layer, and the substrate is immersed in an anodic oxidation solution while the pattern forming layer remains in the concave portion of the concavo-convex structure. The present invention relates to a method for producing a structure having holes, characterized in that holes are formed in the substrate by anodizing the substrate and using the concave side as a starting point .
[0007]
The present invention also provides a method of manufacturing a structure including a step of pressing a pressing member having a plurality of convex structures against a pattern forming layer on a layer to be processed, and a step of separating the member from the pattern forming layer. Using the member having a structure surface size of 500 nm or less and a height of the convex structure of 10 μm or less, the thickness of the pattern forming layer is made thinner than the height of the convex structure of the member, The present invention relates to a method for manufacturing a structure, characterized in that when the distance between the tip of a convex structure and the surface of a layer to be processed is 50 nm or less, the surface of the pattern forming layer is pressed against the concave portion of the member.
[0008]
The size of the convex structure surface of the pressing member here is the diameter when the surface shape is a circle, and the outer diameter when the surface shape is a polygon. The height of the convex structure is several nm to 10 μm, preferably several tens nm to 5 μm.
[0009]
In the method for producing a nanostructure in the present invention, a pattern forming layer having a film thickness thinner than the height of the convex structure of the stamper is provided on the surface of the layer to be processed, and the stamper is pressed against the stamper to form a pattern forming layer. It is preferable to form a convex structure pattern of the stamper.
[0010]
By using a pattern forming layer that is thinner than the height of the convex structure of the stamper, the effect of bubbles is reduced, no vacuum atmosphere is required, and anodization is performed after exposing the work layer by etching after pressing Process. There is no need to perform strict position control in the pressing direction, and a simple nanoprint method can be provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the embodiment of the present invention include the following.
[0012]
As shown in FIG. 4, a stamper (pressing member) on which a pattern of a convex structure is formed and a work layer provided with a pattern forming layer on top of each other are pressed against each other to press the stamper against the pattern forming layer, A method is preferred in which at least the tip of the convex structure approaches the position of a maximum of 50 nm from the surface of the layer to be processed, and the stamper is pulled away to form the convex structure pattern of the stamper on the pattern forming layer.
[0013]
When the pattern forming layer is a material having a low viscosity in proportion to the temperature rise, it is preferable that the pattern forming layer is heated to have an appropriate viscosity at the time of pressing, then pressed, cooled and peeled off. .
[0014]
As shown in FIGS. 2A and 2B, in the nanostructure manufactured by the manufacturing method, the layer to be processed is exposed in the concave portion of the pattern formation layer by dry etching or wet etching technology (step) ) Method is preferable, and as shown in FIG. 2C, a method of forming a concave structure in the work layer by anodizing a nanostructure produced by any one of the above-described manufacturing methods is preferable.
[0015]
The step of exposing the processed layer may be a dry etching method or a wet etching method in which the processed layer in the concave portion of the pattern forming layer is exposed and a concave portion having a depth of 1 nm or more is formed in the processed layer. It is preferable (FIG. 2 (b)).
[0016]
Preferably, the stamper has at least one pair of adjacent concavo-convex structure bodies in which the interval between the convex structures is 1 μm or less.
[0017]
The pattern forming layer is preferably a fluid material such as a resin material containing a resin dissolved in a solvent, an alkoxide or silicon, or a silsesquioxane, which can be applied thinly.
[0018]
The layer to be processed is preferably a metal containing aluminum as a component.
[0019]
It is preferable that the layer to be processed includes a base layer containing a metal other than aluminum as a component and a surface layer containing aluminum as a component.
[0020]
Further, in the method for producing a nanostructure of the present invention, as shown in FIG. 1, a workpiece having a stamper 1 on which a pattern of a convex structure 4 is formed and a pattern forming layer 2 having a thickness smaller than the height of the convex structure 4. The layers 3 are opposed to each other, the stamper 1 is pressed, and at least the tip of the convex structure 4 is brought closer to the range of 50 nm from the surface of the layer 3 to be processed. It is preferable to form a structural pattern.
[0021]
For example, the stamper 1 having at least one concavo-convex is produced by lithography using an electron beam, X-rays, ultraviolet rays, visible light, or the like and a wet etching or dry etching technique, an electron beam direct drawing technique, or an anodic oxidation method. The surface of the convex structure 4 is preferably flat, and when a plurality of convex structures 4 are formed, it is preferable that each vertex is located in the same plane. Further, the convex structure is preferably a triangular grid-like columnar arrangement structure as shown in FIG. Further, as shown in FIG. 5B, a multi-period arrangement composed of several types of regular structures may be used.
[0022]
Further, as shown in FIG. 1, a resin material dissolved in a solvent by spin coating or the like, a resin material containing alkoxide or silicon, or a silsesquioxane or the like can be applied thinly on the work layer 3. A liquid material containing the material as a main component is applied to form the pattern forming layer 2. The film thickness of the pattern forming layer 2 is made thinner than the height of the convex structure 4 of the stamper 1. Next, the stamper 1 is made to face the pattern forming layer 2 and then pressed, and at least the tip of the convex structure 4 of the stamper 1 reaches within a range of 50 nm at the maximum from the surface of the layer 3 to be processed. A convex structure pattern 4 of the stamper 1 is formed on the formation layer 2. The pressing member is a regular array convex structure whose surface layer is made of silicon, nickel or the like, and it is desirable to provide a release material such as a fluororesin or a silane coupling agent in order to improve the peelability.
[0023]
Since the film thickness of the pattern formation layer 2 is thinner than the height of the stamper convex structure 4, it is difficult to cause an influence on the pattern formation layer due to bubbles accumulated in the stamper concave structure 5 and hindering pattern formation. Therefore, it is not necessary to press and release in a vacuum atmosphere. Moreover, it is also preferable to press the workpiece 9 after raising the workpiece 9 to a temperature at which the viscosity of the pattern forming layer 2 is lowered and improving the fluidity.
[0024]
Further, it is preferable that dry etching or wet etching is performed on the structure thus manufactured to remove the pattern formation layer 2 remaining in the pattern formation layer recess 7 and expose the layer 3 to be processed (FIG. 2A ), (B)).
[0025]
For example, if the layer to be processed 3 is a conductive material such as metal and the pattern forming layer 2 is an insulator such as a resin, the exposed layer 3 to be processed is an electrode using the pattern forming layer 2 after pattern formation as a mask. Can be electroplated. After that, by immersing only the pattern forming layer 2 in a solution that dissolves, a structure made of a different material having an uneven structure similar to that of the stamper 1 can be obtained.
[0026]
In addition, as shown in FIG. 2C, in the case where the processing layer 3 is made of a material mainly composed of aluminum, the processing layer obtained by etching the film remaining on the bottom of the pattern forming layer concave portion 7 is used. If anodic oxidation is performed starting from the exposed portion, alumina nanoholes reflecting the pattern of the exposed portion can be obtained. When the pattern forming layer is dissolved in the anodic oxidation solution, as shown in FIG. 6, a protective layer 11 is formed by thinly laminating a metal such as aluminum that dissolves during the anodic oxidation from the top (FIG. 6 ( b)), anodic oxidation may be performed (FIG. 6C).
[0027]
As shown in FIG. 7, when the exposed portion of the layer to be processed is also slightly etched during etching, the pattern forming layer is removed (FIG. 7B), and then anodization may be performed (FIG. 7C )).
Specifically, the anodic oxidation is to immerse a processed layer having a pattern forming layer as an anode in an acidic solution such as an aqueous oxalic acid solution or an aqueous sulfuric acid solution, and apply an electrolysis to perform anodization. Oxidation and dissolution by anodic oxidation starts preferentially from the concave structure portion of the pattern forming layer, so that pores having an array reflecting the concave structure pattern are formed. The voltage applied at this time is generally 2.5 ^-1 [V / nm] times the array period to be formed. For example, in the case of a triangular lattice array with an interval of 100 nm, 40 V may be applied. The average period length of the pores formed by is determined. Therefore, for example, when a regular concave structure in the form of a triangular lattice is formed in the pattern forming layer 2 and a pore is formed from the concave portion 7, even if the arrangement of the regular concave structure is somewhat disturbed, it is naturally corrected by the anodic oxidation applied voltage. It is possible to obtain pores with a regular arrangement.
[0028]
Further, when the pattern forming layer is a material that can be uniformly dissolved at an appropriate rate by the anodic oxidation solution, the etching process can be omitted. When the anodic oxidation is started, the pattern forming layer starts to dissolve, and first, the processing layer at the bottom of the concave structure is exposed, and current flows from there to start forming nanoholes in the processing layer. When the pattern forming layer is a material that is not dissolved by the anodizing solution, nothing is formed on the surface of the layer to be processed.
[0029]
Next, if this is immersed in a solution that dissolves the layer to be processed such as an aqueous phosphoric acid solution, the diameter of the formed nanohole structure can be arbitrarily enlarged.
[0030]
Furthermore, by filling a hole with a functional material by electrodeposition or sputtering, structures having various functions can be obtained. In particular, a magnetic recording medium can be produced by filling the pores with a magnetic material by electrodeposition.
[0031]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0032]
[Example 1]
An example of this invention is shown. Please refer to FIG.
[0033]
The stamper 1 on which the pattern of the concavo-convex structure is formed is pressed opposite to the processing layer 3 having the pattern forming layer 2 having a film thickness thinner than the height of the convex structure 4, and at least the tip of the convex structure 4 is the processing layer. 3, the convex structure pattern of the stamper 1 is formed on the pattern forming layer 2.
[0034]
As an example, a cylindrical convex structure 4 having a diameter of 30 nm and a height of 75 nm arranged on a master disk at an interval of 100 nm is manufactured by an electron beam exposure and a dry etching process to be a stamper 1. Next, as shown in FIG. 1, a processed layer 3 made of silicon oxide (SiO ₂ ) having a thickness of 100 nm and a pattern forming layer 2 made of polymethyl methacrylate (PMMA) are made on a Si substrate 8. To do. PMMA is dissolved in ethyl cellosolve acetate and applied by spin coating. The stamper 1 is opposed to the pattern forming layer 2, pressed at a substrate temperature of 120 ° C. and a load of 1000 kgf / cm ² , held for 30 seconds, cooled to 60 ° C., and then pulled apart (FIGS. 1A and 1B). The height of the convex structure 6 of the pattern forming layer 2 is slightly thicker than the thickness before pressing because the resin of the volume of the concave structure 7 flows, and remains at the bottom of the concave structure 7 due to the nonuniformity of the stamper shape. The resin remains as a thin film.
[0035]
Since the film thickness of the pattern forming layer 2 is thinner than that of the stamper convex structure 4, the air bubbles that have been accumulated in the stamper concave structure 5 and have hindered pattern formation are discharged outside through the stamper concave structure. A fine pattern can be produced without performing means such as pressing at the same time, and since the contact area is small, the pressing pressure can be reduced. Further, since the height of the pattern forming layer convex portion 6 after pattern formation is also determined by the initial film thickness of the pattern forming layer 2 and the stamper 1 shape, it is necessary to finely adjust the pressing load and control the position in the pressing direction. No.
[0036]
[Example 2]
An example of this invention is shown. Please refer to FIG.
[0037]
The structure produced by the method for producing a nanostructure described in Example 1 is dry-etched or wet-etched to remove the resin material remaining in the pattern formation layer recess 7 and expose the layer 3 to be processed. .
[0038]
The stamper 1 described in Example 1 is applied to a workpiece 9 in which the processing layer 3 is aluminum (Al) having a thickness of 100 nm and the pattern formation layer 2 is PMMA. The substrate temperature is 120 ° C. and the load is 1000 kgf / Pressing them against each other under the conditions of cm ² and a holding time of 30 seconds, then cooling to 60 ° C. and then pulling away to produce a structure as shown in FIG. Dry etching is performed in an oxygen atmosphere to remove the resin remaining in the pattern formation layer recess 7 and expose Al (FIG. 2A). Further, etching can be performed in an atmosphere such as a mixed gas of BCl ₃ and O ₂ gas, and Al in the lower part of the pattern forming layer recess 7 can be etched simultaneously to form a recess (FIG. 2B).
[0039]
Thereafter, tin-copper solder electroplating is performed using the pattern forming layer convex portion 6 as a mask and the layer to be processed 3 as an electrode, and only the pattern forming layer convex portion 6 is removed by ultrasonic cleaning with acetone. It is possible to produce solder convex structures arranged in a row.
[0040]
Further, as shown in FIG. 3A, a laminated film 10 of a desired material is formed by sputtering or the like, and only the pattern forming layer convex portion 6 is removed by ultrasonic cleaning with acetone, as shown in FIG. A convex structure can also be produced.
[0041]
[Example 3]
An example of this invention is shown. Please refer to FIG.
[0042]
The stamper 1 described in Example 1 was applied to the workpiece 9 in which the layer to be processed 3 was Al and the pattern forming layer 2 was silsesquioxane, at a substrate temperature of room temperature, a load of 1200 kgf / cm ² , and a holding time. They are pressed against each other under the condition of 30 seconds, and then separated, and dry etching is performed in an atmosphere of argon or SF ₆ to expose Al (FIG. 2A). Next, this is used as an anode in a 0.3 mol / L oxalic acid aqueous solution, and anodization is performed by applying 40 V at a temperature of 16 ° C. Since the exposed portion serves as a starting point for anodic oxidation, it is possible to obtain nanometer-sized holes having a high aspect ratio and reflecting the pattern of the pattern forming layer (FIG. 2C). Since silsesquioxane is insoluble in oxalic acid aqueous solution, it does not need to be removed.
[0043]
[Example 4]
An example of this invention is shown. Please refer to FIG.
[0044]
The stamper 1 on which the pattern of the concavo-convex structure is formed is pressed against the processing layer 3 having the pattern forming layer 2 and pressed away from the stamper 1 to form a concave structure pattern opposite to the convex structure of the stamper 1. To do.
[0045]
As an example, a cylindrical convex structure 4 having a diameter of 30 nm and a height of 75 nm arranged in a triangular lattice pattern at an interval of 100 nm on a master disk made of Si is manufactured by an electron beam lithography and a dry etching process to be a stamper 1. The highest surface of the convex structure 4 is preferably located on the same plane. Next, as shown in FIG. 4, on the substrate 8 made of Si, a processed layer 3 made of silicon oxide (SiO ₂ ) having a thickness of 100 nm and a pattern forming layer 2 made of polymethyl methacrylate (PMMA) having a thickness of 100 nm. Is made. PMMA is dissolved in ethyl cellosolve acetate and applied by spin coating. The stamper 1 is opposed to the pattern forming layer 2, pressed at a substrate temperature of 120 ° C. and a load of 500 kgf / cm ² , cooled to 60 ° C. while being held in that state, and then pulled apart (FIGS. 4A, 4B, ( c)). Since the resin of the volume of the concave structure 7 flows, the thickness around the pressed portion of the pattern formation layer 2 is slightly thicker than the thickness before pressing, and the bottom of the concave structure 7 has a stamper-shaped non-uniformity or Residual resin due to failure to flow remains as a thin film.
[0046]
Depending on the pattern shape, air bubbles may remain in the concave structure 5 of the stamper 1 and the flow of the resin is obstructed, making it difficult to form a pattern completely along the stamper shape. This effect can be reduced by improving the property or making the thickness of the pattern forming layer 2 thinner than the convex structure 4.
[0047]
[Example 5]
An example of this invention is shown. Please refer to FIG.
[0048]
The structure produced by the method for producing a nanostructure described in Example 4 is dry-etched or wet-etched to remove the resin material remaining in the pattern formation layer recess 7 and expose the layer 3 to be processed. .
[0049]
The stamper 1 described in Example 4 is applied to a workpiece 9 in which the processing layer 3 formed on the Si substrate 8 is 200 nm thick aluminum (Al) and the pattern formation layer 2 is PMMA. The substrate is pressed with a substrate temperature of 120 ° C. and a load of 500 kgf / cm ² , and is cooled to 60 ° C. while being held in that state, and then separated to produce a structure as shown in FIG. Etching is performed in an oxygen atmosphere by dry etching to remove only the resin remaining in the pattern formation layer recess 7 and to expose Al (FIG. 6A). Next, as shown in FIG. 6B, an Al protective layer 11 having a thickness of 5 nm is formed by sputtering, and this is immersed in an aqueous oxalic acid solution (0.3 mol / L, 16 ° C.) as an anode. When anodization is performed under the applied voltage, alumina nanoholes as shown in FIG. 6C are formed. The nanoholes are formed from the pattern forming layer recesses 7 and arranged in a triangular lattice pattern with an interval of 100 nm. The protective layer 11 serves to prevent the pattern forming layer 2 from being attacked in an acidic solution, and can be removed by ultrasonic cleaning in a solution that dissolves aluminum, such as an aqueous phosphoric acid solution. Similarly, PMMA can be removed by ultrasonic cleaning in a solvent such as an aqueous phosphoric acid solution or acetone.
[0050]
[Example 6]
An example of this invention is shown. Please refer to FIG.
[0051]
In the steps of the method for manufacturing a nanostructure described in Example 5 to Example 2, dry etching is performed in a mixed etching atmosphere of BCl ₃ and O ₂ , and the resin remaining under the recess 7 of the pattern formation layer It is also possible to etch Al and Al at the same time to produce a recess on the Al surface (FIG. 7A). Thereafter, ultrasonic cleaning in acetone is performed to remove PMMA or ozone ashing (FIG. 7B), and this is used as an anode in an oxalic acid aqueous solution (0.3 mol / L, 16 ° C.). When immersed and anodized under an applied voltage of 40 V, alumina nanoholes as shown in FIG. 7C are formed. The nanoholes are formed from the recesses 13 on the Al surface, and are arranged in a triangular lattice pattern with an interval of 100 nm.
[0052]
[Example 7]
An example of this invention is shown. Please refer to FIG.
[0053]
The pressing member on which the pattern of the concavo-convex structure is formed is pressed against the processing layer having the pattern forming layer, and then separated to form a concave structure pattern opposite to the convex structure of the pressing member on the pattern forming layer.
Next, titanium having a thickness of 10 nm is formed on a substrate made of Si, and an aluminum film having a thickness of 500 nm is further formed thereon to form a layer to be processed. Further, a pattern forming layer made of aluminum alkoxide and having a thickness of 75 nm is formed thereon. Aluminum alkoxide is dissolved in IPA (isopropyl alcohol) and then applied by spin coating. The pressing member described in Example 4 is opposed to the pattern forming layer, pressed at a substrate temperature of 150 ° C. and a load of 1000 kgf / cm ² , cooled to 60 ° C. while being held in this state, and then pulled apart. Since the resin of the volume of the concave structure flows, the thickness around the pressed part of the pattern formation layer is slightly thicker than the thickness before pressing, and the pressing member shape non-uniformity and flow at the bottom of the concave structure Residual resin resulting from the failure to remain remains as a thin film.
[0054]
Next, this is immersed in an aqueous oxalic acid solution (0.3 mol / L, 16 ° C.) as an anode, and an anodic oxidation is performed by applying a voltage of 40V. Aluminum alkoxide hydrolyzes and dissolves gradually in the aqueous oxalic acid solution, so that current begins to flow from the bottom of the concave structure where the layer to be processed is exposed, and that part starts to form alumina nanoholes. To do. Alumina nanoholes by anodization are formed perpendicular to the substrate, and a high aspect ratio structure that cannot be obtained by ordinary photolithography and etching processes can be obtained very easily.
[0055]
When immersed in a phosphoric acid aqueous solution (0.3 mol / L) for about 40 minutes, ordered alumina nanoholes having a diameter of 30 nm and a depth of 500 nm are obtained.
[0056]
Finally, a magnetic recording medium can be produced by filling a hole with a magnetic material by electrodeposition.
[0057]
【The invention's effect】
The present invention is a method for producing a nanostructure by a nanoimprint method and dry etching, wet etching, or anodic oxidation, and a minute concave nanostructure can be easily produced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating Example 1 of the present invention.
FIG. 2 is a cross-sectional view illustrating Embodiments 2 and 3 of the present invention.
FIG. 3 is a cross-sectional view illustrating Embodiments 2 and 3 of the present invention.
FIG. 4 is a cross-sectional view illustrating Example 4 of the present invention.
FIG. 5 is a cross-sectional view illustrating an example of the arrangement of convex structures according to the present invention.
FIG. 6 is a cross-sectional view illustrating a fifth embodiment of the present invention.
FIG. 7 is a cross-sectional view illustrating a sixth embodiment of the present invention.
FIG. 8 is a cross-sectional view illustrating Example 7 of the present invention.
FIG. 9 is a diagram illustrating a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Stamper 2 Pattern formation layer 3 Processed layer 4 Convex structure 5 Concave structure 6 Pattern formation layer convex part 7 Pattern formation layer recessed part 8 Substrate 9 Workpiece 10 Laminated film 100 Stamper 103 Convex structure 104 Resin thin film 105 Substrate 106 Mold area 107 Convex structure 108 Concave structure

Claims (6)

A method of manufacturing a structure having holes,
On the anodized film, a first member having a pattern forming layer made of a material that is dissolved by anodizing treatment is prepared.
A second member having a plurality of convex portions is pressed against the pattern forming layer to form a concavo-convex structure in the pattern forming layer;
With the pattern forming layer remaining in the recesses of the uneven structure, the substrate is immersed in an anodizing solution and anodized,
A method of manufacturing a structure having holes, wherein holes are formed in the substrate starting from the concave side. The method for manufacturing a structure having holes according to claim 1, wherein the pattern forming layer is made of a material whose strength is weaker than that of the second member. The method for producing a structure having holes according to claim 1 or 2, wherein the pattern forming layer contains an alkoxide. 4. The method for manufacturing a structure having a hole according to claim 1, wherein a height of the convex portion of the second member is higher than a thickness of the pattern forming layer. 5. A method for producing a functional structure, comprising a step of filling a functional material into the holes formed by the production method according to claim 1. 6. The method of manufacturing a magnetic recording medium, wherein the functional material according to claim 5 is a magnetic material.

Images