JP5327743B2 - Concave and convex pattern forming method - Google Patents

Description

    The present invention relates to a method for forming an uneven pattern.

  As a typical method of forming a concavo-convex pattern of nanometer to micrometer order on the surface of a substrate, various printing methods are used for forming concavo-convex with relatively large scale, and photolithography is used for forming concavo-convex with relatively small scale. And patterning methods using electron beams are known.

  On the other hand, in recent years, nanoimprint technology has been studied as a next-generation microfabrication technology capable of realizing the above-described scale unevenness pattern formation, in particular, nanometer order unevenness pattern formation more easily and at low cost (for example, non-imprinting technology). (See Patent Documents 1 and 2). This technique is a molding technique in which a stamper on which a nanoscale uneven pattern is formed is pressed against a substrate coated with a resin thin film to transfer the uneven pattern onto the resin thin film. The nanoimprint technology can be broadly divided into a thermal nanoimprint method that heats when a resin thin film is pressed with a stamper, and a photocurable resin as the resin thin film, and light such as ultraviolet rays is emitted while the resin thin film is pressed with a stamper. And an optical nanoimprinting method for irradiation.

S. Y. Chou, P.A. R. Krauss, P.M. J. et al. Penstrom: Appl. Phys. Lett. , 67, 3114 (1995)

L. J. et al. Guo: Adv. Mater. , 19, 495 (2007)

  However, when a concavo-convex pattern is formed using nanoimprint technology, a thin film remains between two adjacent convex portions formed on the substrate surface. When such a thin film (residual film) is present between the convex portions, for example, when a concavo-convex pattern is formed by pressing a stamper against a conductive resin thin film, the electricity between adjacent convex portions on the substrate surface Will bring about continuity.

  The present invention has been made in view of the above circumstances, and when a concavo-convex pattern is formed by pressing a stamper on a thin film, the concavo-convex pattern has substantially no residual film between adjacent convex portions on the substrate surface. It is an object to provide a forming method.

The above-mentioned subject is achieved by the following present invention.
That is, the uneven pattern forming method of the present embodiment is formed of an elastic material on the support surface in a thin film that is formed on the substrate surface and contains a polyimide resin precursor and a carbon nanotube whose surface is modified with a carboxyl group as a main component. At least a concavo-convex pattern forming step for forming a concavo-convex pattern on the surface of the substrate by applying at least one external stimulus selected from heating and light irradiation in a state in which the stamper provided with the concavo-convex mold is pressed. seen including, meets the following formula (1), and the convex portion of the concavo-convex pattern, characterized in that it comprises a carbon nanotubes polyimide resin and surface-modified with a carboxyl group as a main component.
Formula (1) H (thin film) <H (concave / convex) <H (convex)
[In Formula (1), H (thin film) is the hardness of the thin film before the concavo-convex pattern forming step, H (concave / convex type) is the hardness of the concavo-convex type, and H (convex part) is the concavo-convex pattern forming step. The hardness of the convex part which comprises the said uneven | corrugated pattern after implementation is represented. ]

One embodiment of the concavo-convex pattern forming method of this embodiment, the elastic material constituting the uneven mold is preferably a polydimethylsiloxane.

  In another embodiment of the concavo-convex pattern forming method of the present embodiment, the concavo-convex pattern is preferably used as at least one selected from a wiring, an electric circuit, and an electronic element.

  ADVANTAGE OF THE INVENTION According to this invention, when a concavo-convex pattern is formed by pressing a stamper on a thin film, there can be provided a concavo-convex pattern forming method in which a residual film does not substantially exist between adjacent convex portions on the substrate surface.

It is the schematic which shows an example of the uneven | corrugated pattern formation process in the case of forming an uneven | corrugated pattern using the uneven | corrugated type | mold comprised from an elastic material. Here, FIG. 1A is a schematic cross-sectional view showing an example of a state in which a concave-convex mold made of an elastic material is pressed against a thin film, and FIG. 1B is a concave-convex mold made of an elastic material. It is a schematic cross section which shows an example of the uneven | corrugated pattern formed using. It is a top view which shows the uneven | corrugated pattern shape of the sample for evaluation. It is a top view which shows the 1st aspect of the sample for evaluation. It is a top view which shows the 2nd aspect of the sample for evaluation. 4 is a graph showing changes in current value when a direct current is applied to two types of evaluation samples of Example 1. FIG. It is a graph which shows the change of an electric current value when a direct current is applied to the sample for evaluation of Example 1 (sample of the type shown in FIG. 4) and the sample for evaluation of Comparative Example 1 (sample of the type shown in FIG. 4). . 4 is a graph showing changes in current value when a direct current is applied to two types of evaluation samples of Reference Example 1. It is the schematic which shows an example of the uneven | corrugated pattern formation process (conventional uneven | corrugated pattern formation process) in the case of forming an uneven | corrugated pattern using the uneven | corrugated type | mold comprised from an inelastic material. Here, FIG. 8A is a schematic cross-sectional view showing an example of a state in which an uneven mold made of an inelastic material is pressed against a thin film, and FIG. 8B is made of an inelastic material. It is a schematic cross section which shows an example of the uneven | corrugated pattern formed using the uneven | corrugated type | mold.

The uneven pattern forming method of the present embodiment is a thin film formed on a substrate surface and containing as a main component at least one curable material selected from a thermosetting material and a photocurable material, and an elastic material on the support surface. An uneven pattern forming step of forming an uneven pattern on the substrate surface by applying at least one external stimulus selected from heating and light irradiation in a state of pressing a stamper provided with an uneven mold composed of And at least the following expression (1) is satisfied.
Formula (1) H (thin film) <H (concave / convex) <H (convex)
[In Formula (1), H (thin film) is the hardness of the thin film before the concavo-convex pattern forming step, H (concave / convex type) is the hardness of the concavo-convex type, and H (convex part) is the concavo-convex pattern forming step. The hardness of the convex part which comprises the said uneven | corrugated pattern after implementation is represented. ]

  In the concavo-convex pattern forming method of the present embodiment, the concavo-convex hardness H (concave / convex) is greater than the thin film hardness H (thin film). Therefore, a concave / convex pattern is formed when the concave / convex mold is pressed against the thin film. Further, the hardness H (convex portion) of the convex portion of the concave / convex pattern formed on the substrate surface through the concave / convex pattern forming step is larger than the hardness H (convex portion) of the concave / convex type. Therefore, after the concavo-convex pattern forming process is finished, when the stamper is peeled from the concavo-convex pattern-shaped thin film formed on the substrate surface, the concavo-convex mold of the stamper and the convex side surface or top surface of the concavo-convex pattern come into contact, Even if an external force is applied to the convex portion of the concave / convex pattern by the concave / convex mold, the shape of the concave / convex pattern is not impaired.

  The thin film has fluidity when the concave / convex pattern forming step is performed, whereas the concave / convex mold is a solid having a predetermined shape, so that “H (thin film) <H ( The relationship of “concave-convex type” is always satisfied. Moreover, the relationship of “H (concave / convex) <H (convex)” in the formula (1) indicates that the hardness of the cured product constituting the convex part of the concave / convex pattern is higher than the hardness of the elastic material constituting the concave / convex mold. What is necessary is just to select combining the elastic material which comprises an uneven | corrugated type | mold, and the thin film material used for formation of an uneven | corrugated pattern so that it may become large. For example, the above relationship is satisfied if the elastic material is a rubber material such as PDMS and the cured product is a non-elastic material obtained by curing a thin film material mainly composed of a photocurable resin or a thermosetting resin.

  And in the uneven | corrugated pattern formation method of this embodiment, an uneven | corrugated type | mold is comprised from an elastic material. For this reason, when the concave / convex mold is pressed against the thin film, the top surface of the concave / convex convex part can follow the substrate surface exactly, and the concave / convex convex part of the thin film is The resin constituting the thin film is surely extruded by pressurization from a region where the top surface of the convex portion of the mold faces the substrate surface. Therefore, in the concavo-convex pattern produced by the concavo-convex pattern forming method of the present embodiment, substantially no residual film exists between the convex portions adjacent to each other on the substrate surface.

  The reason why the above-described effect is obtained is estimated by the present inventor as follows. That is, not only various substrates with a flat surface on the market, but also a substrate that has been polished so as to obtain extremely high flatness, the substrate surface usually has more or less waviness. . Here, in FIG. 8 and FIG. 1 described below, the heights of the plurality of convex portions provided in the concave-convex mold on the surface of the support (not shown) are all in a state before pressing the concave-convex mold against the thin film. Assume the same. Then, when the concavo-convex mold is made of an inelastic material, as shown in FIG. 8A, there is a gap G (in the figure, between the top surface 22 of the convex portion 20 of the concavo-convex mold 10S and the substrate surface 30. A region indicated by a double-pointed arrow) occurs. Therefore, the thin film material 40 remaining in the gap G forms a residual film 130 between the convex portions 110 of the concave / convex pattern 102 (that is, the bottom portion of the concave portion 120) as shown in FIG. 8B. . On the other hand, when the concavo-convex mold is made of an elastic material as in the concavo-convex pattern forming method of the present embodiment, the top surface 22 of the convex portion 20 of the concavo-convex mold 10E is as shown in FIG. Since the substrate surface 30 can be deformed following the undulation of the substrate surface 30, a gap is not substantially formed between the substrate surface 30 and the top surface 22. Therefore, as shown in FIG. 1B, the residual film 130 is not substantially formed between the convex portions 110 of the concave / convex pattern 100 (that is, the bottom portion of the concave portion 120).

  Next, various materials used in the uneven pattern forming method of the present embodiment and details of each process will be described in more detail.

-Thin film materials-
The thin film material constituting the thin film formed on the surface of the substrate includes at least one curable material selected from a thermosetting material and a photocurable material as a main component, and is a state before the concavo-convex pattern forming step is performed. If it has fluidity | liquidity in (before giving an external stimulus more specifically), it will not specifically limit. The curable material is not particularly limited as long as it is a material that is cured by a polymerization reaction, a condensation reaction and / or a crosslinking reaction by heating or light irradiation, and a known material can be used. It contains a curable component such as a monomer (resin precursor) or a resin having a crosslinking group such as an epoxy group, and may further contain a solvent for dissolving these curable components as necessary.

  A typical example of the thermosetting material is a thermosetting resin. A polyamic acid which is a precursor of a polyimide resin is dissolved in an organic solvent (for example, NMP (N-methyl-2-pyrrolidone)). An example of such a material can be given. Typical examples of the photocurable material include an ultraviolet curable resin. For example, commercially available products include UV nanoimprint resins (trade names; PAK-01, PAK-02) manufactured by Toyo Gosei, and release resins. Fluorine-containing UV nanoimprint resin (made by Asahi Glass, trade name: NIF-A-1) with improved moldability can be used.

  In addition, as a physical property of the hardened | cured material obtained by hardening | curing these curable materials, if the hardness is larger than an uneven | corrugated type | mold, other physical properties will not be specifically limited. However, it is preferable to select a curable material so that a cured product having desired electrical characteristics, light transmittance, refractive index, and other physical properties can be obtained according to the application of the formed uneven pattern. In addition, as long as the hardness of the cured product is larger than that of the concavo-convex mold as described above, the cured product may be an elastic body or an inelastic body, but is usually an inelastic body. preferable.

-Additives-
In addition to the curable material, various additives can be added to the thin film material as necessary. For example, a polymerization initiator or a polymerization accelerator can be added to control the curing reaction. Moreover, a conductive material can be added for the purpose of controlling the conductivity of the cured product, or a high refractive index material such as titanium oxide particles can be added to control the refractive index.

  For example, when it is desired to impart conductivity to the cured product constituting the convex portion of the concave-convex pattern, various conductive carbon particles such as carbon nanotubes (CNT), carbon black, fullerene, etc., and metal fillers are used as the additive (conductive material). Etc. can be used. In addition, when using a carbon nanotube as a conductive material, either a single wall carbon nanotube (SWCNT) or a multi-wall carbon nanotube (MWCNT) may be used. Further, the amount of CNT added in the curable material can be appropriately selected according to the intended electrical characteristics, but 100 parts by mass of the curable material (in the case where the curable material contains a solvent, the solid content is 100 parts by mass). The range of more than 0 parts by mass and 30 parts by mass or less is preferable. When the added amount of CNT exceeds 30 parts by mass, the effect of improving the conductivity with respect to the added amount tends to be saturated, and the dispersibility of CNTs in the curable material because the added amount is too large. May fall.

  Further, when CNT is dispersed in the curable material, the CNT may be dispersed in the curable material as it is. However, in this case, CNT molecules may aggregate due to intermolecular force or the like, and dispersion of CNT in the curable material may be insufficient. In such a case, it is preferable to use CNT that has been solubilized. As a solubilization method, (1) a method of adsorbing a soluble molecule such as a surfactant such as sodium dodecyl sulfate, a polynuclear aromatic compound having a π-conjugated system such as a pyrene derivative, DNA, or RNA to CNT And (2) a method of chemically modifying CNT with a solvophilic solubilizing group, such as forming a carboxyl group at the terminal portion or defective portion of CNT by acid treatment of CNT. Such a solubilization method can be appropriately selected according to the type of solvent in which CNTs are desired to be dissolved / dispersed. For example, when it is desired to improve the solubility / dispersibility of CNT in NMP, which is a good solvent for polyamic acid, which is a precursor of polyimide resin, CNT chemically modified with a carboxyl group by acid treatment can be used.

-Uneven type-
As the concavo-convex type, one made of an elastic material is used. In addition, since it is preferable that an uneven | corrugated type | mold can be utilized repeatedly, it is preferable that this elastic material is a material which is hard to deteriorate by heating or light irradiation. Moreover, when forming an uneven | corrugated pattern using light irradiation, it is preferable that an elastic material has the transmittance | permeability of 50% or more with respect to the wavelength range of the light used when irradiating light. As the elastic material, a known rubber material can be used, and examples thereof include polyolefin-based rubber, fluorine rubber, and silicone rubber. However, among these, a polysiloxane rubber which is a kind of silicone rubber is preferable, and polydimethylsiloxane (PDMS) is most preferably used. There are two reasons for this. First, PDMS has a lower surface energy than other concavo-convex materials. For this reason, it is excellent in releasability without any surface treatment, and when the stamper is peeled after the concavo-convex pattern forming step, the concavo-convex pattern is destroyed or peeled off by adhesion between the concavo-convex pattern surface and the concavo-convex pattern surface. High suppression effect. Second, PDMS has low shrinkage associated with curing. For this reason, when producing a concavo-convex mold made of PDMS by transfer using a master as will be described later, high transfer accuracy can be obtained. PDMS may be modified PDMS in which a part of the repeating units constituting the polymer chain is substituted with a different monomer. In this case, the mode of copolymerization of the modified PDMS may be any of random copolymer type, alternating copolymer type, block copolymer type, or graft copolymer type. Examples of the modified PDMS include poly (dimethylsiloxane) -block-polystyrene (PDMS-b-PS) in the case of a block copolymer type, and include poly (dimethylsiloxane) in the case of a graft copolymer type. Examples include -graft-poly (methacrylate) -co-poly (isobornylacrylate) (PDMS-g-PMIA) and poly (dimethyl siloxane) -graft-poly (methylmethacrylate) (PDMS-g-PMMA). In addition, as a Young's modulus of the elastic material used for an uneven | corrugated type | mold, what is necessary is just about the same level as a general rubber material (about 1MPa-10MPa), but the range of 1MPa-6MPa is more preferable. For example, the above-mentioned PDMS (manufactured by Dow Corning, SYLGARD 184) has a Young's modulus of 2 MPa (Adv. Mater. 2007, 19, 495-513).

  The method for producing the concavo-convex mold is not particularly limited. However, since the concavo-convex mold having a fine and high shape accuracy can be easily produced, the concavo-convex mold is produced using a master produced by patterning combining photolithography and etching. It is preferable to do. Specifically, for example, the concavo-convex mold can be produced by the following procedure. First, a photoresist is applied onto a flat substrate such as a glass substrate, and exposure and etching are performed using a photomask corresponding to the concave / convex pattern, thereby producing a master. Next, with the uncured PDMS film coated on the surface of the support made of a flat substrate such as a glass substrate pressed against the surface on which the concave / convex pattern of the master is pressed, for example, 100 ° C., 1 MPa, 1 hour Under the conditions of pressure and heat treatment. Thereafter, the stamper having a concavo-convex mold made of PDMS formed on the support surface can be obtained by peeling the master.

  In producing the concavo-convex mold, for example, a surface treatment may be performed on the surface of the support in advance in order to strengthen the adhesion between the support and the concavo-convex mold. Such a surface treatment can be appropriately selected in consideration of the combination of the material constituting the support surface and the material constituting the concavo-convex mold. For example, when the support is a glass substrate and the concavo-convex type is composed of PDMS, a silane coupling agent such as HDMS (hexamethyldisilazane) can be used. In addition, the surface of the concavo-convex mold is subjected to a release treatment such as application of a release agent in order to ensure releasability from the thin film material on which the concavo-convex pattern is formed after the concavo-convex pattern forming process. It may be left.

  The shape of the concavo-convex shape in the planar direction and the maximum convex height (or the maximum concave portion depth) are not particularly limited, and can be appropriately selected according to the concavo-convex pattern to be formed. Here, the heights of the convex portions provided in the concavo-convex mold may all be the same or different. Moreover, it is preferable that the maximum height of the convex part provided in the uneven | corrugated type | mold surface exists in the range of 50 nm-10000 nm, and it is more preferable that it exists in the range of 100 nm-5000 nm. When the maximum height of the convex portion is less than 50 nm, it may be difficult to form the convex portion itself. On the other hand, when the maximum height of the convex portion exceeds 10,000 nm, when the concave / convex mold is pressed against the thin film formed on the substrate surface, the convex section is deformed and deformed or the concave / convex mold is easily bent. And such a deformation | transformation and bending may become easy to generate | occur | produce a residual film.

  On the other hand, the minimum pitch between the convex portions is preferably in the range of 10 nm to 100,000 nm, and more preferably in the range of 50 nm to 100,000 nm. When the minimum pitch is less than 50 nm, it may be difficult to produce the concavo-convex mold itself. On the other hand, when the minimum pitch exceeds 100000 nm, when the concavo-convex mold is pressed against the thin film, it becomes difficult for the thin film material to flow in the plane direction of the substrate, or the center of the concave portion is bent so as to protrude toward the substrate side. It becomes easy. For this reason, the shape accuracy of the uneven | corrugated pattern formed may fall. The “minimum pitch between convex portions” means one point on the contour line of the top surface of one convex portion and one point on the contour line of the top surface of another convex portion adjacent to the one convex portion. Means the shortest distance. For example, in the case of a concavo-convex pattern in which a plurality of strip-shaped convex portions are arranged in parallel with an interval of 30 μm, the “minimum pitch between convex portions” is 30 μm.

-Board-
As the surface, any substrate can be used as long as the surface is flat, and various substrates such as a commercially available glass substrate, plastic substrate, ceramic substrate, and semiconductor substrate can be used. However, since the uneven pattern forming method of the present embodiment can suppress the generation of a residual film regardless of the waviness of the substrate surface, it is preferable that the substrate to be used has a somewhat low flatness. In this case, the generation of the remaining film can be further suppressed as compared with the case where an inelastic material such as silicon or metal oxide is used as the material constituting the concavo-convex mold. In addition, when it is going to suppress generation | occurrence | production of a residual film using the uneven | corrugated type | mold comprised from an inelastic material, it is necessary to improve the flatness of a board | substrate fundamentally. However, in order to improve the flatness of the substrate, high precision is required by molding and polishing the substrate, so that the manufacturing and processing costs of the substrate greatly increase with the improvement of the flatness, resulting in practicality as a result. Decreases. However, when forming a concavo-convex pattern using the concavo-convex pattern forming method of the present embodiment, since the generation of a residual film can be suppressed even if the substrate surface is not flat, this means low cost and practicality. Excellent.

  The surface of the substrate may be subjected to a surface treatment using a silane coupling agent or the like in order to improve the adhesion between the substrate and the concavo-convex pattern formed on the substrate surface. For example, when a polyimide resin is used as the main material constituting the concavo-convex pattern, for example, 3-aminopropyltriethoxysilane (APTES) can be used as the silane coupling agent. A silane coupling agent having an amino group such as APTES can form a chemical bond with a carboxyl group. For this reason, when the concavo-convex pattern includes acid-treated CNTs, the CNTs can also be stably fixed to the substrate surface via the carboxyl groups present on the CNT surface.

-Process for forming irregular patterns-
Next, the process for forming the concavo-convex pattern will be described. In the concavo-convex pattern forming method of the present embodiment, there is no particular limitation as long as the concavo-convex pattern is formed through at least the concavo-convex pattern forming step, but usually other steps are appropriately combined before and after these steps. Generally, (1) a thin film forming step for forming a thin film on the substrate surface, (2) a concave / convex pattern forming step, and (3) a peeling step for peeling the concave / convex mold after finishing the concave / convex pattern forming step It is carried out in order. In addition, you may combine another process with these three processes as needed. For example, when the thin film forming process is performed by applying a solution in which a thin film material is dispersed and dissolved in a solvent to the substrate surface, the thin film containing a solvent component is provided between the thin film forming process and the uneven pattern forming process. The drying process which dries can be implemented as needed. Moreover, the baking process which performs baking in order to raise the hardness of the hardened | cured material which comprises an uneven | corrugated pattern after a peeling process can be implemented as needed. Hereinafter, details of each process will be described.

-Thin film formation process-
In the thin film forming step, a thin film is formed on the substrate surface. The formation of the thin film is not particularly limited and can be carried out using a known method, but it is usually preferable to carry out by applying a solution (thin film forming solution) in which the thin film material is dispersed and dissolved in a solvent. As a coating method, a known coating method can be used, and examples thereof include a spin coating method, a dipping method, and a spray coating method. After the thin film forming step, the uneven pattern forming step may be formed as it is. However, if a large amount of solvent remains in the thin film, the concavo-convex pattern forming step is performed after volatilizing the solvent to some extent by natural drying, or the drying step is performed before the concavo-convex pattern forming step. It is preferable to implement. In the drying step, the drying process is performed under conditions that do not lose the fluidity of the thin film. As the drying treatment, heat drying, reduced pressure drying, or the like can be appropriately selected. The drying conditions can be appropriately selected according to the content and boiling point of the solvent contained in the thin film, the vapor pressure, the curing temperature of the solid content, and the like. In addition, the thickness of the thin film before the concavo-convex pattern forming step is not particularly limited, and the maximum convex height of the concavo-convex mold, the volume of the convex portion of the concavo-convex pattern to be formed, the pressing force of the concavo-convex pattern forming step, the concavo-convex pattern It can be appropriately selected in consideration of the fluidity of the thin film when the forming step is performed. However, from a practical viewpoint, the thickness of the thin film is preferably in the range of 50 nm to 10,000 nm, and more preferably in the range of 100 nm to 5000 nm. When the thickness of the thin film is less than 50 nm, since the film thickness is too thin, a concavo-convex pattern having a convex portion having a height corresponding to the concavo-convex pattern may not be formed. Moreover, since the film thickness is too thick when the thickness of the thin film exceeds 10,000 μm, the concavo-convex mold cannot be sufficiently intruded into the thin film in the concavo-convex pattern forming process, and as a result, a residual film may be generated.

-Uneven pattern forming process-
In the concavo-convex pattern forming step, first, a stamper is pressed against the thin film formed on the substrate surface and the surface on the side where the concavo-convex mold is provided. The pressing force at this time can be appropriately selected in consideration of the thickness and fluidity of the thin film, but is preferably in the range of 0.05 MPa to 10 MPa, more preferably in the range of 0.1 MPa to 5 MPa. When the pressing force is less than 0.05 MPa, the pressing force is insufficient, so that the concavo-convex pattern cannot be sufficiently intruded into the thin film in the concavo-convex pattern forming process, resulting in a residual film. is there. Further, when the pressing force exceeds 5 MPa, the elastic material constituting the concavo-convex mold may be greatly deformed and the concavo-convex mold may be damaged.

  Subsequently, with the stamper pressed against the thin film, heating and / or light irradiation is performed according to the composition of the thin film material constituting the thin film and the type of the curable material that is the main component of the thin film material. . The conditions for heating and light irradiation (heating temperature / time, wavelength range / intensity / irradiation time of light to be irradiated) are as follows. However, it can be appropriately selected depending on the composition of the thin film material and the type of the curable material that is the main component of the thin film material, within a range that is greater than the hardness H (concave / convex type) of the stamper.

  When a thermosetting material is used as the main component of the thin film material, heating is performed. The heat treatment in this case may be for the purpose of complete curing that substantially completely cures the thermosetting material, but it is intended for semi-curing that only allows the curing reaction to partially proceed. There may be. For example, when the thermosetting material is polyamic acid, which is a polyimide resin precursor, and the elastic material that forms the concave / convex shape of the stamper is PDMS, the temperature is about 120 ° C. (specifically 80 ° C. for the purpose of semi-curing). It is preferable to perform the heat treatment at a temperature in the range of from ° C to 150C. The reason for this is that heating at a temperature of around 350 ° C. (specifically, in the range of 180 ° C. to 400 ° C.) is necessary in order to complete the imidization reaction by heating to obtain a polyimide resin. This is because, in such a high temperature range, the PDMS constituting the stamper's concave-convex mold is thermally decomposed and deteriorated. When using a thermosetting material that can be completely cured at a temperature lower than the thermal decomposition / degradation of the elastic material constituting the concavo-convex mold, heat treatment is performed for the purpose of complete curing or semi-curing. Also good. In addition, when only the heat treatment (pre-bake treatment) for the purpose of semi-curing is performed in the uneven pattern forming step, the heat treatment (post-bake) for the purpose of complete curing is performed as necessary after passing through the peeling step described later. The baking process which performs a process) can be implemented.

  When a photocurable material is used as the main component of the thin film material, light irradiation is performed. The light irradiation treatment in this case may be for the purpose of complete curing that substantially completely cures the photocurable material, but it is intended for semi-curing that only allows the curing reaction to partially proceed. It may be. Moreover, in the uneven | corrugated pattern formation process, when only the light irradiation process aiming at semi-hardening is implemented, after passing through the peeling process mentioned later, the light irradiation process aiming at complete hardening can be performed as needed. . Light irradiation may be performed from the stamper side or from the substrate side. However, when light irradiation is performed from the stamper side, it is necessary that the support member constituting the stamper and the material constituting the concave-convex mold have translucency with respect to the wavelength range of the light to be irradiated. . Further, in the case of performing light irradiation from the substrate side, it is necessary that the material constituting the substrate has translucency with respect to the wavelength range of the light to be irradiated.

  The execution time of the concavo-convex pattern forming step is appropriately selected according to the progress of the curing reaction and the conditions of heating and light irradiation, but in practice, in the case of thermosetting, the range of 0.5 minutes to 120 minutes is preferable. In the case of photocuring, the range of 1 second to 30 minutes is preferable, and the range of 1 second to 5 minutes is more preferable.

-Peeling process-
After the concavo-convex pattern forming step is completed, the stamper is peeled off from the substrate surface. Thereby, the board | substrate with which the uneven | corrugated pattern which consists of desired uneven | corrugated shape was formed in the surface can be obtained. In addition, you may implement various post processes, such as a baking process, as needed after a peeling process.

-Use of substrate with uneven pattern-
Although the use of the board | substrate with an uneven | corrugated pattern produced by the uneven | corrugated pattern formation method of this embodiment demonstrated above is not specifically limited, It can utilize for the use demonstrated below. For example, when the convex part of the concavo-convex pattern is made of a conductive or semiconductive cured product in which an appropriate amount of a conductive material such as CNT is dispersed in a cured resin matrix, or a cured conductive resin or semiconductive resin Can use a substrate with a concavo-convex pattern as an electronic element such as a wiring, an electric circuit, or a TFT. In applications that require such electrical characteristics, only the convex portions have a predetermined conductivity or semi-conductivity, and the two adjacent convex portions are insulated except for the portions that intentionally conduct both. It is necessary to be. However, in the substrate with a concavo-convex pattern produced by the concavo-convex pattern forming method of the present embodiment, there is substantially no residual film between two adjacent convex portions, and therefore unintended conduction between the two adjacent convex portions. It can be surely prevented from occurring.

In addition, when utilizing a board | substrate with an uneven | corrugated pattern for uses, such as wiring, it is preferable that the hardened | cured material which comprises a convex part contains the material which disperse | distributed CNT in the polyimide resin as a main component. Since polyimide resin is excellent in heat resistance, wear resistance, and chemical resistance, it becomes easy to widely apply and deploy a substrate with an uneven pattern as various electronic components. Here, when giving semiconductivity (10 < ^-12 > S / cm or more and less than 10 < ^-6 > S / cm) to a convex part, the CNT content in a polyimide resin is about 0.1 mass%-about 1 mass%. It is preferable to be in the range. Moreover, when providing electroconductivity (10 ^<-6 > S / cm or more) to a convex part, it is preferable to make CNT content in a polyimide resin into the range of about 1 mass%-30 mass%.

  In addition, if the cured product that constitutes the substrate and the convex portion transmits light in a specific wavelength range and the refractive index of the cured product is larger than the refractive index of the substrate, specify that the substrate and the convex portion are covered. It is possible to dispose a light-transmitting material that transmits light in the wavelength region and has a refractive index smaller than the refractive index of the cured product. In this case, the substrate with a concavo-convex pattern can be used as an optical waveguide or an optical circuit. In addition, for example, a substrate with a concavo-convex pattern can be used as a component in which a flow path for a microreactor is formed, or as a component for a micromachine, its mold, or the like.

  Hereinafter, the concavo-convex pattern forming method of the present embodiment will be described more specifically with reference to examples.

<Evaluation sample shape>
As a sample for evaluation, after forming a plurality of strip-shaped convex portions in parallel as a concavo-convex pattern on the substrate surface, a sample provided with a pair of electrode terminals so as to be parallel or orthogonal to the strip-shaped convex portions Two types were prepared. FIG. 2 is a plan view showing the uneven pattern shape of the evaluation sample. As shown in FIG. 2, the concavo-convex pattern 200 has a shape in which strip-shaped convex portions 210 and concave portions 220 are alternately arranged on the substrate surface. Here, the width X1 of the convex portion is 5 μm, the height h is 1 μm, and the width X2 of the concave portion is 5 μm.

  Moreover, a pair of electrode terminal was arrange | positioned as shown in FIG.3 and FIG.4 so that an uneven | corrugated pattern might be covered. FIG. 3 is a plan view showing a first aspect of the evaluation sample, and is a view showing the evaluation sample 300 in which a pair of electrode terminals 230A and 230B are arranged so as to be parallel to the belt-like convex portion 210. FIG. is there. The electrode terminals 230A and 230B are arranged so as to cover the plurality of convex portions 210 as shown in FIG. The distance D1 between the electrode terminal 230A and the electrode terminal 230B is 90 μm. In the evaluation, a direct current was applied using one of the electrode terminal 230A and the electrode terminal 230B as a positive electrode and the other as a negative electrode.

  FIG. 4 is a plan view showing a second aspect of the evaluation sample, and is a view showing the evaluation sample 310 in which a pair of electrode terminals 230A and 230B are arranged so as to be orthogonal to the belt-like convex portion 210. FIG. . Here, between the convex portion 210B where the tip portion of the electrode terminal 230A is located and the convex portion 210D where the tip portion of the electrode terminal 230B is located, a plurality of convex portions 210C which are not in contact with the electrode terminals 230A and 230B at all. (In FIG. 4, the distance D2 between the electrode terminal 230A and the electrode terminal 230B is set to 90 μm so that there is only one convex portion 210C for simplicity of explanation. In the evaluation, a direct current was applied using one of the electrode terminal 230A and the electrode terminal 230B as a positive electrode and the other as a negative electrode.

<Example 1>
-Fabrication of substrate with uneven pattern-
The board | substrate with an uneven | corrugated pattern shown in FIG. 2 was produced in the following procedures.
First, as a substrate, a glass substrate (S8226, manufactured by Matsunami Glass Co., Ltd.) whose surface was cleaned with a dilute acid and pure water and then surface-treated with a silane coupling agent (APTES) was prepared. Further, as a stamper, an uncured PDMS film spin-coated on the surface of a glass substrate (manufactured by ASONE, slide glass 1204) that has been preliminarily subjected to a heat treatment by dropping a silane coupling agent (HDMS) on the surface in advance. (PDMS is manufactured by Dow Corning, using SYLGARD 184), and the surface on which the concave / convex pattern of the master produced using photolithography and etching is pressed is 100 ° C., 1 MPa, 1 hour. What was prepared by pressurizing and heating under conditions was prepared. The dimensions of the concavo-convex mold of this stamper corresponded to the concavo-convex pattern shown in FIG.

Moreover, the solution which mixed the following composition was used as a solution for thin film formation used when forming a thin film on the substrate surface.
・ Polyamic acid solution (Sigma Aldrich, (Kapton type polyimide precursor)
Poly (pyromellitic dianhydride-co-4,4'-oxydianiline), amic acid solution)
・ NMP (Sigma Aldrich 1-Methyl-2-pyrrolidinone dehydration type)
・ CNT
The CNT is a single wall type carbon nanotube whose surface is modified with a carboxyl group by acid treatment with a nitric acid solution, the diameter of which is about 4-5 nm, and the average length is 0.5-1.5 μm. Degree. The CNT content in the mixed solution having the above composition is 1% by mass in terms of solid content.

  Next, the thin film forming solution was spin-coated on the substrate surface so that the film thickness after the drying treatment was about 0.3 μm, and then the drying treatment was performed at 50 ° C. for 3 minutes. Thereafter, a heat treatment (pre-baking) was performed for 1 hour at a temperature of 120 ° C. and a pressure of 2 MPa with a stamper pressed against the surface of the thin film. Subsequently, after the stamper was peeled off, the substrate on which the concavo-convex pattern was formed was heat-treated (post-baked) at 350 ° C. for 2 hours to obtain a concavo-convex-patterned substrate having the concavo-convex pattern shown in FIG.

-Preparation of sample for evaluation-
After patterning the surface of the obtained substrate with a concavo-convex pattern using photolithography and etching, a pair of electrode terminals (Au film, thickness 0. 03 μm) was deposited, and unnecessary resist was removed. Thereby, the evaluation sample of the 1st aspect and the 2nd aspect was obtained. In Example 1, the width of the electrode terminals 230A and 230B was 2 mm.

(Comparative Example 1)
A sample for evaluation was prepared by forming a concavo-convex pattern in the same manner as in Example 1 except that a stamper produced by the following procedure was used as a stamper.

  Here, the stamper used in Comparative Example 1 was manufactured as follows. First, a thermoplastic resin (Asahi Glass Co., Fluororesin, Cytop CTX-809A) is applied to the surface of a glass substrate (S8226, Matsunami Glass Co., Ltd.) whose surface has been previously treated with a silane coupling agent (APTES). A coating film was formed. Next, this coating film was heated at 180 degrees. Then, a resist is applied to the resin film, and pressure molding (150 ° C., 5 MPa) is performed using a resist film patterned using a photolithography process, thereby forming a groove and obtaining a master. It was. Next, an uncured fluorine-based photocurable resin film spin-coated on the surface of a glass substrate that has been subjected to a cleaning process (manufactured by ASONE, slide glass 1204) (the fluorine-based photocurable resin is manufactured by Asahi Glass, NIF-A-1 In use, the stamper was prepared by performing ultraviolet irradiation treatment (light source wavelength 370 nm, irradiation time 5 minutes, irradiation temperature: room temperature) in a state where the surface of the master plate on which the concave / convex pattern was formed was pressed. . The dimensions of the concavo-convex mold of this stamper corresponded to the concavo-convex pattern shown in FIG. In addition, the material (NIF-A-1) used for manufacturing the uneven mold has a Young's modulus of 2100 MPa and is an inelastic material (Microelectronic Engineering 84 (2007) 973-976).

(Reference Example 1)
In the same manner as in Example 1, a thin film forming solution was spin-coated on the substrate surface so that the film thickness after the drying treatment was about 0.3 μm, followed by a drying treatment at 50 ° C. for 3 minutes. It was. Subsequently, the thin film was cured by post-baking in the same manner as in Example 1.

Subsequently, after forming a resist film on the surface of this thin film, it was exposed using a photomask corresponding to the concavo-convex pattern shown in FIG. 2, and further developed. Thereafter, the thin film was etched by RIE (reactive ion etching) using O ₂ gas as an etching gas so as to correspond to the concavo-convex pattern, and finally the remaining resist was removed to form the concavo-convex pattern. The etching of the thin film by RIE was performed under the condition that the substrate surface was reliably exposed. Thereby, the board | substrate with an uneven | corrugated pattern which has an uneven | corrugated pattern shown in FIG. 2 was obtained. Thereafter, two types of evaluation samples were obtained by forming electrode terminals in the same manner as in Example 1. In Reference Example 1, the width of the electrode terminals 230A and 230B was 0.8 mm.

(Evaluation)
The evaluation is performed by measuring the current value when a DC voltage is applied to the electrode terminals of the two types of evaluation samples prepared in Example 1, Comparative Example 1 and Reference Example 1 while varying the voltage between 0V and 10V. It was evaluated. In addition, for the measurement of the current value, a 6517A (measurement limit is about 1 pA) manufactured by KEITHLEY was used as an ammeter. The results are shown in FIGS. FIG. 5 is a graph showing changes in current value when direct current is applied to the two types of evaluation samples of Example 1, and FIG. 6 is an evaluation sample of Example 1 (shown in FIG. 4). FIG. 7 is a graph showing changes in current value when a direct current is applied to an evaluation sample (type of sample shown in FIG. 4) of Comparative Example 1 and FIG. It is a graph which shows the change of the electric current value at the time of applying a direct current to the sample for evaluation. 5 and 7, the horizontal axis represents the DC voltage (V) applied to the two electrode terminals 230A and 230B shown in FIGS. 3 and 4, and the vertical axis flows between the two electrode terminals 230A and 230B. It represents the amount of current (nA). 5 and 7, the plots indicated by ▲ or △ mean the results of evaluation of the sample for evaluation of the first aspect shown in FIG. 3, and the plots indicated by ● or ○ Means the evaluation result of the evaluation sample of the second embodiment shown in FIG. In FIG. 6, the horizontal axis represents the DC voltage (V) applied to the two electrode terminals 230A and 230B shown in FIG. 4, and the vertical axis represents the amount of current (nA) flowing between the two electrode terminals 230A and 230B. Represent. Further, in FIG. 6, the plots indicated by ● indicate the results of evaluation of the evaluation sample of Example 1 (evaluation sample of the second aspect shown in FIG. 4), and the plots indicated by ▲ Means the evaluation result of the evaluation sample of Comparative Example 1 (the evaluation sample of the second aspect shown in FIG. 4). In FIG. 6, two plot lines are shown as ● and ▲, respectively, which means that measurement was performed at two locations by changing the measurement position.

-About the result of Example 1-
As is apparent from FIG. 5, in the sample for evaluation of the first aspect shown in FIG. 3, the amount of current increases in proportion to the DC voltage, so that the belt-like convex portion 210 has conductivity. I know that. It is also clear from this that the material constituting the convex portion 210 has conductivity.
On the other hand, in the sample for evaluation of the second embodiment shown in FIG. 4, the current value was 0 nA (measurement limit value or less) regardless of the value of the DC voltage. From this, it was found that there is substantially no residual film made of a material having the same conductivity as the convex portion 210 in the concave portion 220.

-Results of Comparative Example 1-
For the sample for evaluation of the first aspect shown in FIG. 3, the current value increased linearly with respect to the voltage as in Example 1 (not shown). On the other hand, the evaluation sample of the second aspect shown in FIG. 4 was compared with Example 1 as shown in FIG. 6 with the scale of the vertical axis enlarged as compared with the case shown in FIG. As a result, in Example 1, regardless of the DC voltage value, the current value was 0 nA (measurement limit value or less), whereas in Comparative Example 1, as the DC voltage value increased, a small amount There was an increase in the amount of current. From this, in the sample shown in Comparative Example 1, it is presumed that a thin and continuous residual film exists in the concave portion 220 so as to conduct between the convex portions 210 adjacent to each other.

-Results of Reference Example 1-
As is clear from FIG. 7, in the sample for evaluation of the first aspect shown in FIG. 3, the amount of current increases in proportion to the DC voltage, so that the belt-like convex portion 210 has conductivity. I know that. It is also clear from this that the material constituting the convex portion 210 has conductivity.
On the other hand, in the sample for evaluation of the second embodiment shown in FIG. 4, the current value was 0 nA (measurement limit value or less) regardless of the value of the DC voltage. This coincides with the fact that the etching by RIE was carried out until the substrate surface was reliably exposed in the production of the uneven pattern of Reference Example 1. And since the tendency of the change of the current value with respect to the direct current is common in Example 1 and Reference Example 1, in Example 1 as well, there is no residual film between two adjacent convex portions 210, Even if some residual film remains, it is only discontinuous between the two adjacent convex portions 210 so that conduction between the two convex portions 210 is impossible. It is estimated that there is no remaining film. In addition, when FIG. 5 and FIG. 7 are compared, the value of the current value differs by about 2.5 times, which is caused by the difference in the width of the electrode terminal. The amount of current per unit width of the electrode terminals 230A and 230B is substantially the same between the first embodiment and the first reference example.

10E Concavity and convexity type 10S (constitution made of elastic material) Concavity and convexity type 20 (constitution made of inelastic material) Convex portion 22 (concavity and convexity) Top surface 30 Substrate surface 40 Thin film material 100, 102 Concavity and convexity pattern 110 ) Convex part 120 Concave part 130 (with concave / convex pattern) Residual film 200 Concave / convex pattern 210, 210A, 210B, 210C, 210D, 210D Convex part 220 Concave part 230A Electrode terminal 230B Electrode terminal 300 Sample 310 for evaluation of the first aspect Second Sample for evaluation of aspect G Gap

Claims (3)

A thin film that is formed on the substrate surface and contains a precursor of polyimide resin and a carbon nanotube whose surface is modified with a carboxyl group as a main component,
By applying at least one external stimulus selected from heating and light irradiation in a state where a stamper provided with an uneven mold made of an elastic material is pressed on the support surface, an uneven pattern is formed on the substrate surface. at least look including an uneven pattern forming step of forming, meets the following formula (1), and the convex portion of the concavo-convex pattern, including the carbon nanotube in which the polyimide resin and the surface-modified with a carboxyl group as a main component An uneven pattern forming method characterized by the above.
Formula (1) H (thin film) <H (concave / convex) <H (convex)
[In Formula (1), H (thin film) is the hardness of the thin film before the concavo-convex pattern forming step, H (concave / convex type) is the hardness of the concavo-convex type, and H (convex part) is the concavo-convex pattern forming step. The hardness of the convex part which comprises the said uneven | corrugated pattern after implementation is represented. ] The method for forming a concavo-convex pattern according to claim 1, wherein the elastic material constituting the concavo-convex mold is polydimethylsiloxane. The uneven pattern, wiring, electrical circuitry, and, the uneven pattern forming method according to claim 1 or 2, characterized in that it is utilized in at least one selected from the electronic device.

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