JP4876261B2 - Method for producing patterned material - Google Patents

Description

  The present invention relates to a method for producing a substance made of a metal or polymer having an arbitrary pattern, particularly a fine pattern.

  In lithography technology, which is a pattern transfer technology for realizing microfabrication, to meet the further demands for miniaturization and integration in the field of semiconductor integrated circuits and photonics, increasing the precision of lithography technology is a very important issue. . However, photolithography, which is the most common technique, has the problem that it is impossible to produce a fine pattern below the light source wavelength of light exposure, so it can be used for fine scales below the light source wavelength. Development of new patterning technology is awaited.

  In recent years, Whiteside has shown that a fine pattern can be easily provided by a soft lithography method such as microcontact printing (μCP) (Non-Patent Document 1). In this method, polydimethylsiloxane (PDMS) elastomer is coated with a thiol derivative and transferred to the gold surface to form self-assembled monolayers (SAMs). This is a method of transferring.

  In addition, as a method of manufacturing a patterned electronic substrate, a stamper having unevenness of the same pattern as the pattern to be formed on the substrate is embossed against a resist film layer formed on the surface of the substrate to be transferred. Nanoimprint technology for transferring the above pattern, in particular, technology for transferring a pattern by pressing a rigid mold into a polymer film heated in the vicinity of Tg has also been reported (Patent Documents 1 and 2).

However, none of these methods can be used for patterning on the surface of a film or sheet made of a water-insoluble polymer or a thermally decomposable polymer that dissolves in an organic solvent. This is because such a polymer has low resistance to an organic solvent and heat, so that a conventional etching method using an organic solvent and a nanoimprinting method using heating damage a film or sheet. On the other hand, it is practically difficult to perform patterning on a highly heat-resistant polymer such as polyimide or a metal by a nanoimprinting technique that involves heating, which requires a considerably high temperature.
Y. Xia, GM Whitesides, Angew. Chem. Int. Ed. 37, 550-575 (1998) US Pat. No. 5,259,926 US Pat. No. 5,772,905

  The main object of the present invention is to provide a new patterning technique capable of forming a fine pattern, which is different from the conventional microcontact printing method and nanoimprint technique.

  The present inventors locally apply to a material to be patterned, for example, a metal or a polymer, by locally applying a liquid that has been originally avoided because of the risk of damaging them. The following inventions have been completed.

1) A method for producing a patterned substance, in which a mold impregnated with a liquid capable of corroding or dissolving a substance is pressed against the substance, and a pattern of the mold is transferred to the substance.

2) Producing a patterned polymer film or sheet in which the material is a water-insoluble polymer film or water-insoluble polymer sheet, and the liquid impregnated in the mold is an organic solvent capable of dissolving the film or sheet The method according to 1).

3) The method according to 2), wherein the water-insoluble polymer film or the water-insoluble polymer sheet is a heat-shrinkable film or a heat-shrinkable sheet.

4) The production method according to 3), wherein the film or sheet is heated and shrunk after the pattern of the mold is transferred to the heat-shrinkable film or heat-shrinkable sheet.

5) The method according to 1) for producing a patterned metal or semiconductor, wherein the substance is a metal or semiconductor, and the liquid impregnated into the mold is an acidic liquid capable of corroding the metal or semiconductor.

6) The method according to any one of 1) to 5), wherein the template is made of polydimethylsiloxane.

7) The manufacturing method according to any one of 1) to 5), wherein the mold pattern is a pattern comprising reliefs and / or slits.

It is a schematic diagram of a nano pillar structure. 2 is a SEM photograph showing the structure of film A before heat shrink made in Example 1. FIG. 2 is a SEM photograph showing the structure of film A after heat shrinkage prepared in Example 1. FIG. 2 is a SEM photograph showing the structure of a film B before heat shrink produced in Example 1. FIG. 2 is a SEM photograph showing the structure of a film B after heat shrink produced in Example 1. FIG. 2 is a SEM photograph showing the structure of a film C before heat shrink produced in Example 1. 2 is a SEM photograph showing the structure of a film C after heat shrinkage prepared in Example 1. 4 is a SEM photograph showing the structure of a film D after heat shrink created in Example 2. FIG. 4 is a SEM photograph showing the structure of a film E after heat shrink created in Example 2. FIG. 4 is a SEM photograph showing the structure of a film F after heat shrinking created in Example 2. FIG. 4 is an optical micrograph showing the structure of a negative mold made of a multi-network structure type water-soluble gel prepared in Example 3. FIG. 3 is an optical micrograph showing the structure of a PVA film created in Example 3. It is an optical microscope photograph which shows the structure of the negative mold which consists of polyacrylamide gel prepared by the test example.

  The method of the present invention uses a material to be patterned, a liquid capable of corroding or dissolving the material, and a mold having a desired pattern immersed therein, and pressing the mold against the material to form a pattern of the template. Is transferred to a substance.

  The method of the present invention can be applied to all substances that require patterning. For example, patterning can be performed for metals such as gold, silver and nickel, semiconductors such as silicon, polymers, inorganic oxides such as glass (silicon oxide) and titanium oxide, and the like.

  In particular, the method of the present invention is particularly useful in that it can effectively pattern a water-insoluble polymer having low resistance to heat and organic solvents, for which there has been no effective patterning method.

  Representative examples of water-insoluble polymers that can be patterned by the method of the present invention include styrene polymers, polysulfones, polyether sulfones, polyalkyl siloxanes, polyalkyl methacrylates such as polymethyl methacrylate, or polyalkyl acrylates, Conjugated diene polymers such as polybutadiene and polyisoprene, poly-N-vinylcarbazole, polylactic acid, polycaprolactones, polyalkylacrylamides, polycarbonates, polyesteramides, polyanhydrides, poly (amino acids), polyorthoesters , Polyacetals, polycyanoacrylates, polyetheresters, poly (dioxanone) s, poly (alkylene alkylates), polyethylene glycol and polyorthoesters Polymers, biodegradable polyurethane mixtures, or copolymers thereof, styrene-maleic anhydride alternating copolymers, divinyl ether-maleic anhydride alternating copolymers, ethylene-vinyl acetate polymers and acyl-substituted cellulose acetates, polyurethanes, polychlorinated Mention may be made of vinyl, polyvinyl fluoride, poly (vinylimidazole), chlorosulfonate polyolefins, mixtures thereof and copolymers thereof.

  The method of the present invention relates to a process for producing a patterned polymer film or sheet, preferably based on a film or sheet formed from the above water-insoluble polymer. Hereinafter, in this specification, a film meaning a thin film and a sheet meaning a flat plate are collectively referred to as a film or the like.

  In order to form a polymer film or the like having a finer pattern, it is particularly preferable to use a heat-shrinkable film produced by uniaxial or biaxial stretching using a polymer such as polycarbonate or polycycloolefin as a raw material. . After the pattern of the mold is transferred to a heat-shrinkable film or the like, the polymer film having a fine pattern in which the transferred pattern is further reduced can be manufactured by heat-treating and shrinking the pattern. The heat-shrinkable film is not limited to those using the above-mentioned polymers such as polycarbonate and polycycloolefin as a raw material, and may be a water-insoluble polymer film as long as it is a film made of a polymer having a property of shrinking by heating. Either a water-soluble polymer film or a water-soluble polymer film can be used.

  The liquid capable of corroding or dissolving the substance to be patterned means a liquid capable of altering, destroying or dissolving the substance described above. For example, acidic liquids such as dilute hydrochloric acid and dilute sulfuric acid for metals, organic solvents for water-insoluble polymers, aqueous solutions for water-soluble polymers, and liquids such as hydrofluoric acid solutions for glass . The specific liquid capable of corroding or dissolving the substance to be patterned varies depending on the substance, but such liquid is known for each substance, and the selection or determination of the liquid depends on the substance. Can be selected easily.

  Examples of water-insoluble polymers include polystyrene, polycarbonate, polysulfone, polyethersulfone, polyalkylsiloxane, polyalkyl methacrylates or polyalkyl acrylates such as polymethyl methacrylate, polybutadiene, polyisoprene, poly-N-vinylcarbazole, For polymers selected from the group consisting of polylactic acid, poly-ε-caprolactone, polyalkylacrylamide, and copolymers thereof, carbon tetrachloride, dichloromethane, chloroform, benzene, toluene, xylene, carbon disulfide, etc. , And can be used as an organic solvent capable of dissolving the polymer (hereinafter referred to as a good solvent).

  In the present invention, selective application of a liquid capable of corroding or dissolving a substance to be patterned to the substance is performed through a mold impregnated with the liquid. A specific operation is to immerse a mold having an arbitrary pattern in a liquid selected in advance so that the liquid is impregnated inside the mold and press the mold against a substance to be patterned.

  The mold that can be used here needs to be made of a material that is resistant to and can be impregnated with a liquid that can corrode or dissolve a substance to be patterned. Examples of such a material include a crosslinkable polydimethylsiloxane elastomer, a crosslinked polyvinyl alcohol gel, a bisphenol-based crosslinked resin, an olefin-based crosslinked resin, and a crosslinked rubber. Among these, a crosslinkable polydimethylsiloxane (PDMS) elastomer is most preferable.

  In the present invention, it is necessary to form an arbitrary pattern, particularly a pattern made of reliefs and / or slits, on the mold made of the above-mentioned material. The relief referred to in the present invention means the unevenness provided on the surface of the mold, and therefore the pattern made of the relief means an arbitrary pattern drawn by the unevenness provided on the solid surface. In addition, the slit referred to in the present invention is not limited to the elongated groove formed so as to penetrate the mold, and means a void portion having any shape such as a circle, a polygon, and the like. The pattern is not limited to an elongated groove formed so as to penetrate the mold, and refers to an arbitrary pattern drawn by a void portion having a circle, a polygon or any other shape. The relief and the slit may coexist in one mold.

  Any of the conventionally known methods can be used for patterning on the mold. For example, lithography, soft lithography, and other methods (edited by the Society of Polymer Science, “Fine Processing Technology” (Basic), 2002, The template can be directly patterned using NTS, etc.) or the imprinting technique described above. Further, the mold of the present invention may be produced as a negative mold by adding a prepolymer (for example, PDMS prepolymer) of each material described above to the surface of a substance having a desired pattern, followed by curing and polymerization.

  In order to impregnate the mold with the liquid, the entire mold or a portion that contacts the substance to be patterned may be immersed in the liquid. The immersion time may be appropriately adjusted according to the size of the mold and the penetration speed, but can be performed within a range of about 10 seconds to 10 hours.

  It is preferable to adjust the pressure for pressing the template against the material to be patterned while observing the amount of the template intruded into the material (the height at which the convex portion of the template intrudes into the material). By this adjustment, a pattern having an arbitrary recess depth can be formed on the material.

  If the template is prepared using a heat-shrinkable material such as N-isopropylacrylamide, the pattern of the template can be further refined by performing heat treatment after patterning the template. In addition, a water-containing polymer, for example, a water-soluble gel such as polyacrylamide gel that has been patterned is immersed in a non-aqueous solvent such as acetone, or air-dried to remove the water contained in the gel and remove the gel. By shrinking, the pattern of the mold can be further refined. For example, when creating a negative mold by adding a prepolymer to the surface of a material having a desired pattern, and curing and polymerizing, a honeycomb porous body made of a water-insoluble polymer is used as the material having the desired pattern Then, after adding a water-soluble gel prepolymer (such as acrylamide) to the gel, the honeycomb porous body is dissolved by adding chloroform or the like to form a negative mold made of polyacrylamide gel. it can. Here, the honeycomb-like porous body has a structure in which minute holes (including depressions) oriented in the vertical direction of the film are provided in a honeycomb shape (in a honeycomb shape) in the plane direction of the film. (For example, Japanese Patent Laid-Open No. 8-311231 as a patent document). The holes may communicate with surrounding holes existing in the plane direction inside the film. A porous thin film provided with pores having a uniform pore diameter in such a regular arrangement such as a honeycomb shape has a regular pore having irregular pore diameters, shapes or depths. It can be understood as a completely different structure from a porous thin film.

  The negative mold made of polyacrylamide gel prepared by the above method has a pattern made of protrusions corresponding to the pores of the honeycomb-like porous body. When this negative mold is immersed in 50% or 70% acetone, the moisture contained in the gel moves to acetone, and as a result, the entire negative mold contracts, and the projection pattern is refined.

When a negative mold is prepared using the above water-soluble gel, the surface on the side in contact with the prepolymer such as a honeycomb-like porous body that is the first mold for the negative mold is treated with, for example, ultraviolet-ozone treatment (Yabu et al. , Literature Colloids and Surfaces A, 284-285, 301-304 (2006)) It is preferable to treat it by other known methods to make it hydrophilic. As a method for making the surface of such a substance hydrophilic, in addition to ultraviolet-ozone treatment, hydrophilic coating such as gelatin coating and polyvinyl alcohol coating, oxygen plasma, corona discharge and the like can be mentioned. A method is also available. In addition to polyacrylamide gel, agarose gel, chemically cross-linked PVA gel, polyvinyl alcohol gel cross-linked with Cu ²⁺ , polyacrylic acid gel cross-linked with Fe ³⁺ can be used as water-soluble gel. is there. A multi-network structure type gel described in International Publication No. 03/093337 pamphlet can also be used in the present invention. This multi-network structure type gel is advantageous in that it has excellent mechanical strength and can be pressed against a substance to be patterned at a higher pressure.

  The following examples illustrate the details of the present invention. However, these examples do not limit the present invention.

  A nanopillar structure A (3.3 mm × 3.3 mm) made of polystyrene having the structure shown in FIG. 1 (projections are 1000 nm in diameter × height (height difference between projections and depressions) is a 1000 nm cylinder and the spacing between the projections is 1000 nm). And Chou et al. (Nature, 417, 836-838 (2002)).

  From the top of the nanopillar structure A placed in a petri dish with a diameter of 9 cm, 20 g of 10: 1 mixture of SILPOT184W / C (PDMS) manufactured by Dow Corning and a crosslinking catalyst was cast, and a crosslinking reaction was performed at 200 ° C. for 2 hours. Thereafter, the nanopillar structure was dissolved and removed with benzene to produce a negative type PDMS template A. After the entire mold A was immersed in benzene for 1 minute, the mold A was taken out and its surface was dried.

  The mold A prepared above was placed on a 10 mm × 10 mm heat shrinkable film (Mitsui Chemicals, APL8008T, MD × TD 1.5 times stretched) and compressed. The strength of compression was controlled while measuring the amount of mold invaginated into the film. After holding the compression for 1 minute, the mold A was peeled off to recover the patterned film A. After observing the surface structure of the produced film A using an optical microscope, a scanning electron microscope (SEM), and an atomic force microscope (AFM, SPI400), the film is heated to 90 to 95 ° C. on a hot stage. After heat shrinkage, the surface structure was observed again.

  In the structure observation by AFM, in the film A before heat shrinkage (FIG. 2), a nanopillar structure having a diameter of the top of the convex portion of 1000 nm, an unevenness height difference of 820 nm, and an interval between the convex portions of 1000 nm was observed. Further, in the film A after heat shrinkage (FIG. 3), a nanopillar structure having a diameter of 780 nm at the top of the convex portions, a height difference of the convex and concave portions of 750 μm, and a spacing between the convex portions of 690 nm was observed.

  Further, a nanopillar structure B (3.3 mm × 3.3 mm) made of polystyrene having a convex portion of a cylinder having a diameter of 750 nm × a height of 750 nm and a spacing of the convex portion of 750 nm was prepared, and the same operation as described above was performed. Thus, a film B (FIG. 4) having a nanopillar structure in which the top of the convex portion has a diameter of 480 nm, the height difference of the concave and convex portions is 600 μm, and the interval between the convex portions is 580 nm. Further, this film B is heated to 90-95 ° C. on a hot stage and thermally contracted, and a film having a nanopillar structure with a diameter of the top of the convex portion of 440 nm, an unevenness height difference of 530 nm, and an interval between the convex portions of 500 nm (FIG. 5). ) Was produced.

  Further, a nanopillar structure C (3.3 mm × 3.3 mm) made of polystyrene having a convex part of a cylinder having a diameter of 500 nm × a height of 500 nm and a spacing of the convex part of 500 nm was prepared, and the same operation as described above was performed. Then, a film C (FIG. 6) having a nanopillar structure in which a column with a diameter of 200 nm at the top of the convex portion, a height difference of the concave and convex portions of 160 nm, and an interval between the convex portions is 400 nm was produced. Further, this film is heated to 90 to 95 ° C. on a hot stage and thermally contracted, and a film having a nanopillar structure having a convex portion top diameter of 200 nm, a concave and convex height difference of 130 nm, and a convex portion interval of 240 nm (FIG. 7). Was made.

  Chloroform solution (5mg / mL) 12ml, 5ml and 2ml in which polystyrene and Cap polymer were mixed at a ratio of 10: 1 were cast into a 9cm petri dish, and the chloroform was evaporated in an air flow with a relative humidity of 70%. , Honeycomb porous bodies D to F having a diameter of 9 cm (D: hole diameter 8 μm, film thickness 15 μm, E: hole diameter 4.4 μm, film thickness 10 μm, F: hole diameter 1.3 μm, film thickness 5 μm) were prepared.

  20 g of 10: 1 mixed SILPOT184W / C (PDMS) manufactured by Dow Corning Co., Ltd. and a crosslinking catalyst was cast from above the honeycomb-shaped porous body, and after removing the bubbles by reducing the pressure, the mixture was removed at 200 ° C. for 2 hours. A cross-linking reaction was performed. The honeycomb porous body was dissolved and removed with benzene, and PDMS molds D to F corresponding to the negative type of the honeycomb porous body were produced. The whole mold was immersed in benzene for 1 minute, and then the mold was taken out and its surface was dried.

  Each mold prepared above was placed on a 10 mm × 10 mm heat-shrinkable film (Mitsui Chemicals, APL8008T, MD × TD 1.5 times stretched) and compressed. The strength of compression was controlled while measuring the amount of mold invaginated into the film. After holding the compression for 1 minute, the mold was peeled off and the patterned films D to F were collected. The surface structure of the produced film was observed using an optical microscope, a scanning electron microscope (SEM), and an atomic force microscope (AFM, SPI400).

  In the film shape, indentations aligned in a honeycomb shape were observed. The distance between the centers of the indentations was 10 μm for film D, 4.7 μm for film E, and 1.5 μm for film F. Furthermore, each film was heated to 90-95 ° C. on a hot stage and thermally contracted, and the surface structure was observed again. While maintaining the regularity of being aligned in a honeycomb shape, the distance between the centers of the recesses was the film. D changed to 6.7 μm (the depth of the depression was approximately 250 nm, FIG. 8), film E changed to 3.0 μm (FIG. 9), and film F changed to 1.0 μm (FIG. 10). Moreover, although the film after heat shrinkage was slightly wrinkled, the interference color of light was clearly observed and had transparency.

  10 ml of a chloroform solution (5 mg / mL) mixed with a 10: 1 ratio of polystyrene and Cap polymer was cast into a 9 cm petri dish, and the chloroform was evaporated in an air flow with a relative humidity of 70% to obtain a honeycomb having a diameter of 9 cm. A porous material G (pore diameter 11 μm, film thickness 10 μm) was prepared. One side of this honeycomb-shaped porous body was subjected to ultraviolet-ozone treatment for 30 minutes with Iwasaki Electronics OC-250615-D + A.

To the honeycomb-shaped porous body after the ultraviolet ray-ozone treatment is added 20 mL of a solution containing 25.0 wt% acrylamide and 23.8 wt% AWP (manufactured by Toyo Gosei), and irradiated with 360 nm UV rays. Thus, a multi-network structure type water-soluble gel was formed by crosslinking.

  After cross-linking, chloroform was added to dissolve and remove the honeycomb-shaped porous body to obtain a negative mold (20 mm × 20 mm) made of a water-soluble gel having a multi-network structure type (FIG. 11). This negative mold had a pattern in which protrusions shaped like a cylinder having a diameter of 10 μm and a height of 10 μm were arranged in a honeycomb shape with a period of about 10 μm.

A 15 mm × 15 mm polyvinyl alcohol film was prepared by casting a 10 wt% polyvinyl alcohol aqueous solution onto a 0.2 mL glass substrate and forming it at room temperature. The negative mold prepared above was placed on this film, and the negative mold was pressed against the PVA film with a pressure of 50 N / cm ² . After holding the compression for 1 minute, the mold was peeled off, and the patterned film G was collected. The surface structure of the produced film was observed using an optical microscope (FIG. 12). In the film, pits aligned in a honeycomb shape were observed.

Test example

  10 ml of a chloroform solution (5 mg / mL) mixed with a 10: 1 ratio of polystyrene and Cap polymer was cast into a 9 cm petri dish, and the chloroform was evaporated in an air flow with a relative humidity of 70% to obtain a honeycomb having a diameter of 9 cm. -Like porous body H (pore diameter 11 μm, film thickness 10 μm) was prepared. One side of this honeycomb-shaped porous body was subjected to ultraviolet-ozone treatment for 30 minutes with Iwasaki Electronics OC-250615-D + A.

  20 mL of an aqueous solution containing acrylamide, 25.0% by weight of N, N′-methylenebisacrylamide and ammonium peroxide sulfide is added to the honeycomb-shaped porous body, and N, N, N ′, N′-tetramethylethylenediamine is further added. Was added to crosslink the acrylamide. Three types of acrylamide concentrations were prepared: 1.0 mmol, 0.69 mmol, and 0.33 mmol. After cross-linking, chloroform was added to dissolve and remove the honeycomb-like porous body to obtain a negative mold (8 mm × 15 mm) made of polyacrylamide gel. This mold had a pattern in which protrusions in the shape of a cylinder having a diameter of 11 μm and a height of 10 μm were arranged in a honeycomb shape at intervals of about 11 μm (FIG. 13).

When the negative mold made of polyacrylamide gel was dried for 2 hours while degassing, the interval between the protrusions was 8.2 μm. Moreover, when it heated at 65 degreeC and dried for 4 hours, the space | interval of a processus | protrusion became 4.9 micrometers. Further, when the negative mold heated to 65 ° C. and dried for 4 hours was placed in water for 2 hours and 12 hours, the distance between the protrusions was 7.0 μm and 9.3 μm, respectively.

  Next, when negative molds consisting of three types of acrylamide concentrations of 1.0 mmol, 0.69 mmol, and 0.33 mmol were soaked in 100% water, 50% acetone, and 75% acetone for 2 hours, negative molds consisting of each acrylamide concentration were obtained. When the period of the protrusion when immersed in 100% water is 1, 1.05 is 0.95 / 50% acetone, 0.90 / 75% acetone, 0.69 mmol is 0.83 / 50% acetone, 0 .56 / 75% acetone, 0.33 mmol, 0.60 / 50% acetone, 0.56 / 75% acetone.

  Moreover, when a negative mold comprising three types of acrylamide concentrations of 1.0 mmol, 0.69 mmol, and 0.33 mmol was dried at 45 ° C. for 30 hours, when the period of the protrusions of each negative mold before the start of drying was 1, 1.0 mmol The protrusion period changed to 0.44, the protrusion period changed to 0.32 at 0.69 mmol, and the protrusion period changed to 0.23 at 0.33 mmol.

  The method of the present invention is based on an idea different from the conventional microcontact printing method and nanoimprint technology, and can produce various patterned metals and polymers. In particular, based on a heat-shrinkable polymer film or a heat-shrinkable polymer sheet, a polymer film or a polymer sheet having micropatterning exceeding the diffraction limit can be produced. Such a film or sheet can be used for the production of an optical film such as a light diffusing film, in particular, a moth-eye type antireflection film that requires a structure having a wavelength of visible light or less, and also as a substrate for cell culture. Is available.

Claims (8)

A method for producing a patterned substance, wherein a mold impregnated with a liquid capable of corroding or dissolving a substance is pressed against the substance, and a pattern of the mold is transferred to the substance. The method of claim 1, wherein the substance is a heat shrinkable film or a heat shrinkable sheet. A method for producing a patterned polymer film or sheet, wherein the material is a water-insoluble polymer film or a water-insoluble polymer sheet, and the liquid impregnated in the mold is an organic solvent capable of dissolving the film or sheet. The method according to 1 or 2. The manufacturing method according to claim 2 or 3, wherein after the pattern of the mold is transferred to the heat-shrinkable film or heat-shrinkable sheet, the film or sheet is heat-shrinked. The method of claim 1, wherein the material is a metal or semiconductor and the liquid impregnating the mold is an acidic liquid capable of corroding the metal or semiconductor. The method according to claim 1, wherein the template is made of polydimethylsiloxane. The method according to claim 1, wherein the template is made of a water-soluble gel. The manufacturing method in any one of Claims 1-5 whose pattern of a casting_mold | template is a pattern which consists of a relief and / or a slit.