JP2007253354A - Method for producing minute three-dimensional metal structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing fine three-dimensional metal structures which is unnecessary to carry out treatment in vacuum, improves production efficiency and the degree of freedom of processing, and makes it possible to arrange a large number of the fine metal structures in a three-dimensional space while they are prevented from being contacted with each other. <P>SOLUTION: The method for producing the fine three-dimensional metal fine structures having an optional three-dimensional shape includes the first process for forming a polymer structure having a fine three-dimensional structure by a two-photon absorption finely shaping method in which a reformed resin with an electron donor discharging electrons by being irradiated with light added to a light curable resin is irradiated with short pulse laser beams and the second process for forming a metal film on the surface of the polymer structure by applying electroless plating to the polymer structure formed in the first process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a three-dimensional metal microstructure, and more specifically, a three-dimensional metal microstructure with a resolution of nm order, for example, a fine metal three-dimensional structure having a size of about 0.1 to several μm. The present invention relates to a method for producing a three-dimensional metal microstructure suitable for use in creating a body.

  In general, a focused ion beam apparatus is mainly used for producing a three-dimensional metal microstructure.

  Here, the focused ion beam apparatus refers to a focused ion beam (Focused) which is an ion beam obtained by focusing an ion beam obtained from a metal ion source using an electromagnetic field lens or an aperture so that the beam diameter is several μm or less. Ion Beam).

  This focused ion beam has a very high energy and can cut the metal by irradiating the metal surface. When the focused ion beam is irradiated in an organometallic gas atmosphere, the gas is decomposed. A metal can be deposited or deposited on the material surface.

  Therefore, when such a focused ion beam generator for generating a focused ion beam is used, a three-dimensional metal microstructure can be produced with a resolution of about 10 nm (see Non-Patent Document 1).

  However, in the above-described method for producing a three-dimensional metal microstructure using a focused ion beam, the processing such as metal cutting or metal film formation or deposition on the object surface by irradiation of the focused ion beam is performed in a vacuum. Since this method needs to be performed by irradiating a focused ion beam, the entire configuration of the apparatus becomes large, requiring a large space and cost.

  Further, in the above-described method for producing a three-dimensional metal microstructure using a focused ion beam, when a large number of metal microstructures are arranged in a three-dimensional space without being in contact with each other, each metal structure is separated by some sort. Therefore, it has been pointed out that it is difficult to produce such a metal microstructure.

  Furthermore, in this method of manufacturing a three-dimensional metal microstructure using a focused ion beam, a region to be cut by the focused ion beam, film formation, deposition, or the like is an extremely small region (for example, a diameter of about 10 nm). The production efficiency is inferior because it is a region), and it takes a long time (for example, several hours) to produce one three-dimensional metal microstructure. There is a problem that it is unsuitable and its industrial use is limited.

As another method for producing a three-dimensional metal microstructure, a two-photon absorption fine modeling method is also known (see Non-Patent Document 2).

  This two-photon absorption fine modeling method is based on the following principle. That is, when the short pulse laser beam is condensed on the photocurable resin, two-photon absorption occurs only at the condensing point where the light intensity is high. Therefore, the curing reaction of the photocurable resin proceeds locally there, and a polymer is obtained. At this time, since the two-photon absorption occurs only in the central portion where the light intensity is particularly strong among the condensing points, the cured spot can be produced with a size exceeding the diffraction limit of light. Therefore, it is possible to produce a three-dimensional polymer structure having an arbitrary shape by scanning light condensing three-dimensionally in a photocurable resin.

  According to the above-described two-photon absorption fine modeling method, for example, the minimum spot obtained when performing the two-photon absorption fine modeling method using a femtosecond titanium sapphire laser with a wavelength of 800 nm is about 100 nm. By using a short pulse laser, a three-dimensional microstructure can be produced with a resolution of about 100 nm.

  Here, the processing method by the two-photon absorption microfabrication method will be described specifically by taking as an example the case of producing a three-dimensional model of a cow with a length of 8 μm shown in FIGS. 1 (a), (b), and (c). A three-dimensional view of a cow with a body length of 8 μm in which the curing spots in the photocurable resin are arranged one by one while irradiating the photocurable resin with a short pulse laser beam and scanning the condensing point three-dimensionally. Complete (see FIG. 1A). Once the solid figure of 8μm long cows with cured spots arranged one by one is removed, the uncured photocurable resin is removed with ethanol or the like (see FIG. 1 (b)), and the solid model of 8μm long cows. Is obtained (see FIG. 1C).

  In addition, as a system for irradiating a short pulse laser beam and performing a two-photon absorption fine modeling method, for example, a femtosecond laser beam is irradiated as a short pulse laser beam as shown in FIGS. A system has been proposed. A system for performing a two-photon absorption fine modeling method by irradiating a short pulse laser beam as shown in FIGS. 2A and 2B is already well known as disclosed in Non-Patent Document 2. Therefore, the detailed configuration and description of the operation are omitted.

  However, the above-described two-photon absorption fine modeling method has a problem that the obtained three-dimensional microstructure is limited to a polymer structure, and a three-dimensional metal microstructure cannot be produced.

In addition, as a well-known document regarding silver reduction using carbazole, there is one presented as Non-Patent Document 3, for example, and as a known document concerning plating on plastic, for example, one presented as Non-Patent Document 4 is there.
Y. Hirayama, Y. et al. Suzuki, S .; Tarucha and H.M. Okamoto, J. et al. J. et al. Appl. Phys. Part2-Letter 24, L516 (1985) S. Kawata, H .; -B. Sun, T .; Tanaka and K.K. Takada, Nature 412, 697 (2001) H. Katagi, H .; Kasai, S .; Okada, H .; Oikawa, H .; Matsuda and H.M. Nakanishi, Polym. Adv. Technol. 11,778 (2000) G. O. Mallory, J.M. B. Hajdu, Electroplating: Fundamentals and Applications, American Electroplaters and Surface Finishers Society, Orlando, FL 1990. V. P. Menon, C.I. R. Martin, Anal. Chem. 67, 1920 (1995)

  The present invention has been made in view of the above-described various problems of the prior art, and the object of the present invention is to provide a three-dimensional metal microstructure that does not require processing in a vacuum. It is intended to provide a method for manufacturing a body.

  Another object of the present invention is to provide a method for producing a three-dimensional metal microstructure with improved production efficiency and freedom of processing.

  Furthermore, an object of the present invention is to provide a method for manufacturing a three-dimensional metal microstructure that enables a large number of metal microstructures to be arranged in a three-dimensional space without contacting each other. is there.

  In order to achieve the above object, a method for producing a three-dimensional metal microstructure according to the present invention is a combination of a two-photon absorption fine shaping method and electroless plating.

  Such a method for producing a three-dimensional metal microstructure according to the present invention does not use an ion beam, and therefore can produce a three-dimensional metal microstructure without requiring processing in vacuum. In addition, the production efficiency and the processing freedom can be remarkably improved.

  That is, in the method for producing a three-dimensional metal microstructure according to the present invention, a two-photon absorption fine molding method and electroless plating are used to produce a three-dimensional metal microstructure. As explained in the above-mentioned “Background Technology”, the microfabrication method collects a short pulse laser beam in a photocurable resin to cause two-photon absorption, and a cured polymer is obtained only at that portion. This is a manufacturing method of a three-dimensional microstructure used.

  The structure obtained by this two-photon absorption fine shaping method is limited to a polymer structure, but in the method for producing a three-dimensional metal fine structure according to the present invention, it is obtained by the two-photon absorption fine shaping method. A metal structure such as silver is applied to the polymer structure by electroless plating, thereby producing a three-dimensional metal microstructure. When electroless plating is used, the three-dimensional structure can be uniformly coated with a metal film regardless of the size of the three-dimensional structure.

  In other words, in the conventional method of manufacturing a three-dimensional microstructure using the focused ion beam, since the modeling is performed using the ion beam, it is necessary to perform the modeling in a vacuum. In the method for producing a three-dimensional metal microstructure, since a laser is used when performing the two-photon absorption fine modeling method, no treatment in a vacuum is required.

  In the method of manufacturing a three-dimensional metal microstructure according to the present invention, a plurality of microstructures can be simultaneously formed by using laser interference or a microlens array when producing a polymer structure by a two-photon absorption microfabrication method. Is easy to form.

  Furthermore, in the method for producing a three-dimensional metal microstructure according to the present invention, no matter how many polymer structures form a metal film by electroless plating, the electroless plating process is only immersed in a solution, In addition, it is possible to perform metal coating over a large area.

  Therefore, the production efficiency of the manufacturing method of the three-dimensional metal microstructure according to the present invention is remarkably improved as compared with the conventional focused ion beam apparatus through the entire process.

  The method for producing a three-dimensional metal microstructure according to the present invention is a two-photon absorption microfabrication method using a modified resin in which an electron donor that emits electrons when irradiated with light is added to a photocurable resin. A polymer structure is prepared by the above method, and a metal is coated on the surface of the polymer structure by electroless plating.

  Furthermore, the manufacturing method of the three-dimensional metal microstructure according to the present invention is a method of producing a polymer structure by a two-photon absorption microfabrication method using two kinds of resins, a photocurable resin and a modified resin, By subjecting the surface of the structure to electroless plating, metal coating is selectively performed on the polymer structure portion made of the modified resin.

  Note that examples of the electron donor that emits electrons when irradiated with light include a substance having at least one carbazole group in the molecular structure, a substance having R-CHO in the molecular structure, Si, and Ga. There are semiconductors such as Ge or GaAs.

  Here, for example, carbazole is excited by light irradiation, and the carbazole molecule itself becomes a conductive or electron donor. If there is a cation that wants an electron around the excited molecule, the cation will receive the electron and be reduced to a stable metal.

  That is, according to the present invention, when a substance having at least one carbazole group in the molecular structure is used as an electron donor, it is prepared from a modified resin obtained by adding an electron donor to a photocurable resin. In the polymer structure part, by performing electroless plating in the light-irradiated state, the reducing agent is present in the polymer structure, and the reduction reaction proceeds on the surface of the polymer structure and the metal is deposited. Will come to be.

  By using the photo-curing resin and the modified resin according to the method of the present invention, it is possible to selectively coat a metal on one three-dimensional microstructure by electroless plating, and a large number of metal microstructures can be formed. They can be arranged in a three-dimensional space without being in contact with each other.

Among these inventions, the invention described in claim 1 is a method for producing a three-dimensional metal microstructure having an arbitrary three-dimensional shape, in which an electron donor that emits electrons when irradiated with light is used as a photocurable resin. A first step of forming a polymer structure having a three-dimensional microstructure by a two-photon absorption fine modeling method by irradiating a modified resin added to a short pulse laser beam, and the first step A second step of forming a metal film on the surface of the polymer structure by performing electroless plating on the formed polymer structure.

  The invention according to claim 2 of the present invention is a method for producing a three-dimensional metal microstructure having an arbitrary three-dimensional shape, wherein a two-photon is irradiated with a short pulse laser beam on a photocurable resin. For a modified resin in which a first polymer structure having a three-dimensional microstructure is formed by an absorption microfabrication method and an electron donor that emits electrons when irradiated with light is added to the photocurable resin. The first polymer structure and the second polymer are irradiated with a short pulse laser beam to form a second polymer structure having a three-dimensional microstructure by a two-photon absorption fine modeling method. A first step of forming a third polymer structure comprising the structure, and electroless plating on the third polymer structure formed by the first step, and selectively performing the second step. Metal on the surface of the polymer structure It is obtained as a second step of forming a.

  The invention according to claim 3 of the present invention is the invention according to any one of claims 1 or 2, wherein the electron donor has at least one carbazole in the molecular structure. It has a group.

  The invention according to claim 4 is the invention according to claim 3, wherein the electron donor is 1,6-di (N-carbazole) -2,4-hexazine. It is made to be a polymer.

  The invention according to claim 5 of the present invention is the invention according to claim 3 of the present invention, wherein the electron donor is a polymer of 9H-carbazole-9-ethyl methacrylate. It is a thing.

  The invention according to claim 6 of the present invention is the invention according to claim 1 or 2 of the present invention, wherein the electron donor has R-CHO in the molecular structure. It is what I did.

  The invention according to claim 7 of the present invention is the invention according to any one of claims 1 or 2, wherein the electron donor is a semiconductor. .

  Since the present invention is configured as described above, there is an excellent effect that a three-dimensional metal microstructure can be produced without performing processing in a vacuum.

  In addition, since the present invention is configured as described above, it has an excellent effect that the production efficiency and the degree of freedom in processing when producing a three-dimensional metal microstructure can be remarkably improved.

  Furthermore, since the present invention is configured as described above, there is an excellent effect that a large number of metal microstructures can be arranged in a three-dimensional space without being in contact with each other.

  Hereinafter, an example of an embodiment of a method for producing a three-dimensional metal microstructure according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a flow chart showing an example of the processing steps of an embodiment of a method for manufacturing a three-dimensional metal microstructure according to the present invention. The method for manufacturing a three-dimensional metal microstructure according to the present invention comprises: Using a material added with an electron donor that emits electrons by irradiating light to the curable resin (referred to as “modified resin” as appropriate in this specification), the two-photon absorption microfabrication method is used to make fine particles. A two-photon absorption microfabrication process (step S1), which is a first process for producing a simple polymer structure, and an electroless process, which is a second process for performing metal coating on the surface of the polymer structure produced in step 1 by electroless plating A plating process (step S2).
By performing the two processes of step S1 and step S2, a three-dimensional metal microstructure can be formed.

  Hereinafter, it demonstrates in detail, referring the experimental result which this inventor performed.

(1) Electroless plating on modified resin First, the results of experiments conducted by the present inventor will be described in detail with respect to an electron donor that emits electrons when irradiated with light.

  Here, for example, carbazole is known as a substance that emits electrons when irradiated with light.

  The carbazole is excited by being irradiated with light, and the carbazole molecule itself becomes conductive and becomes an electron donor that emits electrons.

  Therefore, when a cation that desires an electron exists around a carbazole molecule (carbazole excited molecule) excited by irradiation with light, the cation receives the electron and is reduced to a stable metal. That is, carbazole acts as a reducing agent in the state where light is irradiated.

  Therefore, the inventor of the present application forms a polydiacetylene having a carbazole group such as 1,6-di (N-carbazol) -2,4-Hexadiyne shown in FIG. 4 (hereinafter referred to as “PDA” as appropriate). In order to examine whether or not the prepared polymer can be electrolessly plated without a sensitizer such as a catalyst, an experiment was conducted in which electroless silver plating was performed on PDA nanocrystals.

  In this experiment, first, PDA nanocrystals shown in FIG. 4 were prepared by a reprecipitation method, and the PDA nanocrystals (diameter 150 nm) prepared by this reprecipitation method were mixed with an aqueous silver nitrate solution and an ammoniacal silver nitrate solution. It was immersed in an aqueous solution and irradiated with visible light while being kept at 40 ° C.

  As a result, silver cations in the ammoniacal silver nitrate aqueous solution were reduced on the PDA nanocrystals, and precipitation of silver particles having a particle diameter of 5 to 15 nm was confirmed on the surface of the PDA nanocrystals (diameter 150 nm). That is, it was possible to perform electroless plating directly on a polymer formed from PDA.

  Next, PDA was dissolved in N, N-dimethylacetamide and a 100 mM PDA N, N-dimethylacetamide solution (hereinafter referred to as “PDA solution” as appropriate) adjusted to 100 mM was used on the polymer surface after curing. Experiments for electrolytic silver plating were performed.

  In this experiment, first, 30 μl of a PDA solution was dropped on a glass substrate and cured while keeping at 45 ° C.

  Then, on the cured PDA, an ammoniacal silver nitrate aqueous solution in which an aqueous ammonia solution (5.5%) is mixed with a 0.25M silver nitrate aqueous solution at a volume ratio of 10: 6 is dropped, and ultraviolet rays are applied in a state where the temperature is kept at 45 ° C. Silver plating was given by irradiation for hours.

  As a result, when the surface of the PDA was observed with a scanning electron microscope (SEM: Scanning Electron Microscopy) and an energy analysis X-ray spectrometer (EDS: Energy Dispersion X-ray Spectrometry), silver deposition was confirmed.

  From the above experimental results, it was confirmed that the PDA itself can perform electroless plating without a catalyst or a reducing agent.

  Here, as shown in FIG. 5, the PDA solution has no absorption in the near-infrared region (wavelength near 800 nm) which is the wavelength region of the femtosecond titanium sapphire laser used in the two-photon absorption fine stereolithography.

  Therefore, using a system as shown in FIGS. 2A and 2B, femtosecond titanium sapphire laser light (wavelength 796 nm, pulse width 140 fs) with a laser power of 294 mW is condensed by the objective lens and applied to the PDA solution. Then, an experiment was conducted in which the optical modeling was performed by the two-photon absorption fine modeling method.

  As a result, polymerization did not occur sufficiently in the PDA solution, and when it was continuously irradiated, PDA crystals were precipitated as shown in FIG. This is because the polymerization was difficult to occur because the PDA did not contain a polymerization initiator or a polymerization terminator.

  Therefore, a fine polymer structure is produced by performing optical modeling by the two-photon absorption fine modeling method using a PDA solution to which a polymerization initiator or a polymerization terminator is added (step S1 in FIG. 3), and the produced fine By applying electroless plating to the polymer structure (step S21 in FIG. 3), a three-dimensional metal microstructure can be produced.

(2) About the manufacturing method of the three-dimensional metal microstructure using the electron donor which has a carbazole group (2-1) Metal precipitation to the photocurable resin which added the electron donor which has a carbazole group It demonstrated above. As described above, the polymer surface obtained by curing the PDA solution could be silver-plated by electroless plating, but optical modeling by the two-photon absorption fine modeling method using the PDA solution could not be performed. It was.

  This is because the PDA does not contain a polymerization initiator or a polymerization terminator as described above. Therefore, using a commercially available photocurable resin containing a polymerization initiator or a polymerization terminator, the photocuring is performed. An experiment was conducted in which electroless plating was performed on a modified resin obtained by adding a PDA solution to a conductive resin.

  First, using three types of acrylic photocurable resins KC1102, KZ and Z7012C manufactured by JSR Corporation as commercially available photocurable resins, a concentration of 10% by weight of the PDA solution (about Z7012C) is applied to each of these photocurable resins. Was added at a concentration of 12% by weight) to prepare three types of modified resins.

  Then, one drop of three types of photocurable resins to which the PDA solution as these three types of modified resins was added was dropped on the glass substrate, and the droplets formed by the dropping were irradiated with ultraviolet rays and cured. .

  After curing, the polymer surface was washed with acetone, and a 0.2M silver nitrate aqueous solution was added dropwise to the cured polymer after washing, and ultraviolet rays were irradiated for 1 hour while keeping the temperature at 45 ° C.

  After that, it was thoroughly washed with water and acetone and then dried. After drying, the mixture was mixed with 0.2M silver nitrate aqueous solution and 5.5% ammonia aqueous solution at a volume ratio of 10: 6 while maintaining the temperature at 45 ° C. A solution prepared by mixing a neutral silver nitrate aqueous solution and a 1.9 M glucose solution used as a reducing agent in a volume ratio of 1: 1 was dropped, and silver plating was performed by electroless plating.

  According to this experimental result, it was confirmed that silver plating was formed on all three types of modified resins.

  Furthermore, the resistance value of Z7012C subjected to silver plating was 7.5Ω at a silver plating width of 1 mm, and energization was confirmed.

  In addition, regarding optical modeling by the two-photon absorption fine modeling method in the above-described three types of photocurable resins, it is difficult to perform high-precision optical modeling because KZ has high viscosity. On the other hand, it was confirmed that KC1102 and Z7012C can perform high-precision optical modeling.

  Next, an experiment relating to the concentration of the PDA solution capable of photofabrication will be described. Z7012C was used as the photocurable resin.

  Then, an experiment was conducted to confirm whether or not the photopolymerization can be performed by the two-photon absorption fine modeling method for the modified resin obtained by adding 16% by weight, 30% by weight, and 54% by weight of the PDA solution to Z7012C.

  As the short pulse laser beam, a femtosecond titanium sapphire laser beam was used, and the femtosecond titanium sapphire laser beam was condensed by an objective lens to cure the modified resin with two photons and perform optical modeling.

  As a result, in the modified resin to which 54% by weight of the PDA solution was added, PDA crystals were precipitated and polymerization did not occur. Moreover, the modified resin to which 30% by weight of the PDA solution was added could not be three-dimensionally shaped.

  It was confirmed that the modified resin to which 16% by weight of the PDA solution was added with respect to the modified resin to which the PDA solution was added at a high concentration described above was capable of three-dimensional modeling (see FIG. 7).

  Here, as described above, the carbazole group in the PDA emits electrons when irradiated with ultraviolet rays in electroless plating, and forms a metal film by reducing nearby metal ions.

  That is, in the present invention, the reducing agent is present in the photocurable resin to which the PDA solution is added. From this, an experiment was conducted for the case where no reducing agent was used during electroless plating.

  First, using a modified resin obtained by adding 16% by weight of a PDA solution to Z7012C, an experiment was conducted to confirm the state of metal deposition when no reducing agent was added during electroless plating.

  That is, a 0.25M silver nitrate aqueous solution is applied to a resin obtained by adding a PDA solution of 16% by weight to Z7012C on a glass substrate and irradiating the droplets formed by the dropping with ultraviolet rays to cure. Was dropped and irradiated with ultraviolet rays while being kept at 45 ° C.

  Thereafter, it was washed with water and acetone and dried. After drying, a 0.25M silver nitrate aqueous solution was dropped again and left for 24 hours to perform silver plating.

  After completion of such silver plating, it was sufficiently washed with water and acetone and dried, and the deposited state and surface state of silver were observed with SEM and EDS.

  As a result, an SEM image obtained by SEM shown in FIG. 8A, a reflected electron beam image obtained by a reflection type polarization microscope shown in FIG. 8B, and a silver mapping image obtained by EDS shown in FIG. 8C (FIG. 8C). ) Confirmed that silver was precipitated on the surface of the cured modified resin. In addition, since silver precipitation on the surface of the modified resin is rough, it is considered that silver plating excellent in conductivity can be formed by performing silver plating using a reducing agent.

  From the above experimental results, it was confirmed that when a modified resin obtained by adding a PDA solution to Z7012C, which is a commercially available acrylic photocurable resin, can be metal-plated by electroless plating. Moreover, it can be said that it is preferable to use a reducing agent at the time of electroless plating.

  Therefore, using a modified resin obtained by adding a PDA solution to a commercially available photo-curing resin, an optical modeling is actually performed by a two-photon absorption fine modeling method, and a fine polymer structure manufactured by a two-photon absorption micro molding method is used. An experiment was carried out in which electroless silver plating treatment was applied.

  First, a femtosecond titanium sapphire laser beam (wavelength 796 nm, pulse width 140 fs) with a laser power of 350 mW is condensed and irradiated to a modified resin obtained by adding 15% by weight of a PDA solution to Z7012C. The modified resin was cured with two photons to form a cube.

  After the laser irradiation, the uncured resin was washed with acetone to produce a cube (hereinafter referred to as “polymer cube” as appropriate).

  To the polymer cube thus produced, an ammoniacal silver nitrate aqueous solution in which a 0.25M silver nitrate aqueous solution and a 5.5% ammonia aqueous solution were mixed at a volume ratio of 10: 6 was dropped, and ultraviolet rays were irradiated for 30 minutes while being kept at 45 ° C. .

  Then, it was washed with water and acetone and then dried, and after that, a solution prepared by mixing the above-described ammoniacal silver nitrate aqueous solution and 1.9 M glucose solution used as a reducing agent in a volume ratio of 1: 1 was added dropwise and kept at 45 ° C. Silver plating was carried out by electroless plating after standing for 1 minute.

  FIGS. 9A and 9B show SEM images of the polymer cube electrolessly plated as described above, and it was confirmed that the surface of the polymer cube was silver-plated. In the SEM images shown in FIGS. 9A and 9B, the glass substrate is also silver-plated.

  Thus, by adding an electron donor that emits electrons when irradiated with light to a commercially available photocurable resin, a three-dimensional microstructure is produced by the two-photon absorption fine structure method, and the produced three-dimensional A metal coating by electroless plating can be applied to the fine structure, and a three-dimensional metal fine structure can be produced.

  In the above, a method for producing a three-dimensional metal microstructure using a photocurable resin to which an electron donor having a carbazole group is added has been described. Next, a three-dimensional metal microstructure is converted into a three-dimensional fine structure. A method for selectively manufacturing part of the structure will be described.

(2-2) Production of a three-dimensional microstructure comprising two types of photocurable resins To selectively produce a three-dimensional metal microstructure as part of a three-dimensional microstructure, first, a PDA solution A three-dimensional microstructure is produced by using two types of photocurable resins, ie, a photocurable resin to which is not added and a photocurable resin (modified resin) to which a PDA solution is added.

  In the experiment of the present inventor, three-dimensional modeling is performed by two-photon absorption microfabrication using three-dimensional modeling using a commercially available photocurable resin and a modified resin obtained by adding a PDA solution to the photocurable resin. A microstructure was prepared.

  Specifically, stereolithography was performed by a two-photon absorption microfabrication method using two types of photocurable resins of KC1102 and Z7012C to which a PDA solution was added.

  First, KC1102 was dropped on a glass substrate, and femtosecond titanium sapphire laser light (wavelength 796 nm, pulse width 140 fs, laser energy 20 nJ) was applied to the objective lens (magnification 60 times, NA). = 1.4) By condensing and irradiating, the droplets were cured with two photons so as to form a cube. The irradiation time was 200 milliseconds per spot.

  After such laser irradiation, uncured KC1102 was washed with acetone to produce a cube (hereinafter referred to as “polymer cube” as appropriate).

  Thereafter, a modified resin obtained by adding 10% by weight of a PDA solution to Z7012C is dropped from above the polymer cube prepared as described above, and femtosecond titanium sapphire laser light (wavelength is applied to the droplet formed by the dropping. By condensing and irradiating 796 nm, pulse width 140 fs, laser energy 20 nJ) with an objective lens (60 × magnification, NA = 1.4), the droplet is cured with two photons so as to form a ring with a diameter of 1 μm. I let you. The irradiation time was 200 milliseconds per spot.

  After completion of such laser irradiation, the uncured modified resin was washed with acetone to produce a ring having a diameter of 1 μm on the polymer cube.

  As described above, when the two-photon absorption fine modeling method is used, a polymer cube is formed with a photocurable resin to which no PDA solution is added, and a ring is formed on the polymer cube with a modified resin. A dimensional fine structure can be produced from two types of resins, and the photocurable resin can be cured with two photons to localize the required polymer structure to the intended portion.

(2-3) Site-selective silver coating Next, two types of photocurable resins prepared according to the above (2-2) (two types of photocurable resins of KC1102 and Z7012C added with a PDA solution) A three-dimensional microstructure comprising a polymer cube and a ring having a diameter of 1 μm formed on the polymer cube, and a volume ratio of 10% by volume of a 0.25M silver nitrate aqueous solution and a 5.5% ammonia aqueous solution. : Ammonia silver nitrate aqueous solution mixed in 6 was added dropwise and irradiated with ultraviolet rays for 30 minutes while being kept at 45 ° C.

  Thereafter, it is washed with water and acetone and then dried. After drying, a solution obtained by mixing the aqueous ammoniacal silver nitrate solution and the 1.9M glucose solution used as a reducing agent in a volume ratio of 1: 1 is added to the polymer structure. The solution was dropped and left at a temperature of 45 ° C. for 1 minute, and silver plating was performed by electroless plating.

  FIGS. 10 (a) and 10 (b) show SEM images of the polymer structure electrolessly plated as described above. As shown in FIG. 10A, silver particles are hardly present on the surface of the polymer cube formed of KC1102. On the other hand, as shown in FIG. 10B, silver particles are densely present on the ring surface formed of the modified resin (Z7012C to which the PDA solution is added).

  In this way, a three-dimensional microstructure is prepared using two types of photocurable resins, a photocurable resin to which no PDA solution is added and a photocurable resin (modified resin) to which a PDA solution is added. By applying electroless plating to the created three-dimensional microstructure, the three-dimensional metal microstructure can be selectively produced as a part of the three-dimensional microstructure.

  Furthermore, as will be described below, a large number of metal microstructures can be arranged in a three-dimensional space without contacting each other.

(2-4) Fabrication of metal microstructures arranged in a three-dimensional space As described above, with the technique of the present invention, only a specific part of a polymer structure is coated with a resolution of about 100 nm. can do.

  Therefore, according to the method of the present invention, for example, a cylindrical polymer structure 12 made of a photocurable resin is formed on the glass substrate 16 as shown in FIG. A three-stage ring-shaped metal microstructure 14 (made of a modified resin and subjected to metal coating by electroless plating) is formed without contacting each other. Thus, a large number of metal microstructures can be arranged in a three-dimensional space without being in contact with each other, such as making it possible to produce a three-dimensional space arrangement metal microstructure as described above.

  Fabrication of such a structure is difficult with the conventional technique, and is one application example of the technique of the present invention.

(3) Substances contributing to metal deposition during electroless plating As described above, in the above-described embodiment, the substances contributing to metal precipitation during electroless plating are carbazole groups. However, this point will be described in detail below.

First, the inventor of the present application
a. Whether the substance that contributes to metal deposition during electroless plating is really a carbazole group,
b. Does the electron donor having a carbazole group need to be polydiacetylene,
c. Electroless plating was performed in the state of being irradiated with ultraviolet rays and kept at 45 ° C. Can plating be performed only by irradiation with ultraviolet rays without heating to 45 ° C,
d. What is the metal reduction mechanism of carbazole?
An experiment was conducted to confirm the above.

  First, by using 10,12-nonacosadiynoic acid (hereinafter, appropriately referred to as “NSA”) having a carboxyl group and an alkyl chain on the side chain of diacetylene shown in FIG. 12, the carbazole group contributes to silver precipitation. An experiment was conducted to confirm whether or not

  That is, NSA was dissolved in N, N-dimethylacetamide to prepare a 100 mM NSA N, N-dimethylacetamide solution (hereinafter, appropriately referred to as “NSA solution”) adjusted to 100 mM. And the modified resin which added 10 weight% of NSA solution to Z7012C was dripped on the glass substrate, and the droplet formed by the said dripping was irradiated with ultraviolet rays, and was hardened.

  Next, an ammoniacal silver nitrate aqueous solution in which a 0.25M silver nitrate aqueous solution and a 5.5% aqueous ammonia solution are mixed at a volume ratio of 10: 6 is dropped onto the cured modified resin, and ultraviolet rays are kept for 30 minutes while being kept at 45 ° C. Irradiated.

  Thereafter, the resin is sufficiently washed with water and acetone and then dried, and after the drying, a modified resin obtained by curing a solution prepared by mixing the ammoniacal silver nitrate aqueous solution and the 1.9 M glucose solution used as a reducing agent at a volume ratio of 1: 1. The solution was dropped on the plate and kept at 45 ° C. for 1 minute, and then subjected to silver plating by electroless plating.

  As a result of these experiments, almost no silver was deposited on the surface of the cured modified resin.

  From this, it was confirmed that the carbazole group contributes to metal deposition in electroless plating.

  Here, polydiacetylene is a π-conjugated polymer expected as a third-order nonlinear optical material, and as is clear from the fact that it is a single crystal, its molecular structure is 100% regular, and those The aggregation state of molecules is always single.

  The recent increase in conductivity in conducting polymer research is a result of the improvement of the structural regularity of polydiacetylene, and is said to have important implications for physical property research.

  However, when polydiacetylene is added to the photocurable resin in this experiment, the structural regularity of the polydiacetylene is lost, the excellent properties of polydiacetylene are not exhibited, and there is no merit of using polydiacetylene. End up.

  Therefore, 9H-Carbazol-9-ethylmethacrylate (hereinafter referred to as “CEM” as appropriate) containing carbazole in the same acrylic monomer as Z7012C shown in FIG. 13 is used for electroless plating on the resin surface in the present invention. An experiment was conducted to confirm whether a substance containing carbazole enabling metal deposition needs to have diacetylene as a basic skeleton.

  That is, CEM was dissolved in N, N-dimethylacetamide to prepare a 100 mM CEM N, N-dimethylacetamide solution (hereinafter referred to as “CEM solution” as appropriate) adjusted to 100 mM.

  And the modified resin which added 10 weight% of CEM solutions to Z7012C was dripped on the glass substrate, and the droplet formed by the said dripping was irradiated with ultraviolet rays, and was hardened.

  Next, an ammoniacal silver nitrate aqueous solution in which a 0.25M silver nitrate aqueous solution and a 5.5% aqueous ammonia solution are mixed at a volume ratio of 10: 6 is dropped onto the cured modified resin, and ultraviolet rays are kept for 30 minutes while being kept at 45 ° C. Irradiated.

  Thereafter, the resin is sufficiently washed with water and acetone and then dried, and after the drying, a modified resin obtained by curing a solution prepared by mixing the ammoniacal silver nitrate aqueous solution and the 1.9 M glucose solution used as a reducing agent at a volume ratio of 1: 1. Then, it was left for 2 minutes while being kept at 45 ° C., and silver plating was performed by electroless plating.

  As a result of these experiments, as shown in FIG. 14, it was confirmed that silver plating was performed by electroless plating also by adding a CEM solution to a commercially available acrylic photocurable resin Z7012C.

  From this, it was confirmed that the electron donor having carbazole need not have diacetylene as a basic skeleton.

  Next, in the above-described experiments, when performing electroless plating, it was heated to 45 ° C. and irradiated with ultraviolet rays for 30 minutes to 1 hour, but it was only irradiated with ultraviolet rays without heating to 45 ° C. An experiment was conducted to confirm whether electroless plating is performed.

  That is, a modified resin 1 in which 10% by weight of CEM solution is added to KC1102 and a modified resin 2 in which 10% by weight of CEM solution is added to Z7012C are prepared, and these modified resin 1 and modified resin 2 are prepared on a glass substrate. The droplets formed by the dropping were irradiated with ultraviolet rays and cured.

  Then, an ammoniacal silver nitrate aqueous solution in which a 0.25M silver nitrate aqueous solution and a 5.5% ammonia aqueous solution are mixed at a volume ratio of 10: 6 is added dropwise to each of the cured modified resin 1 and modified resin 2, respectively. (23 ° C.) for 30 minutes.

  Thereafter, the resin is sufficiently washed with water and acetone and then dried, and after the drying, a modified resin obtained by curing a solution prepared by mixing the ammoniacal silver nitrate aqueous solution and the 1.9 M glucose solution used as a reducing agent at a volume ratio of 1: 1. 1 and the modified resin 2 were dropped respectively, and left for 1 minute in a state kept at 45 ° C., and silver plating was performed by electroless plating.

  The results are shown in FIGS. 15 (a) and 15 (b), and it was confirmed that silver plating was applied to both the modified resin 1 and the modified resin 2.

  Further, the resistance value per 1 mm of the silver plating formed on the modified resin 1 in which 10% by weight of the CEM solution was added to KC1102 was 9Ω, and it was formed in the modified resin 2 in which 10% by weight of the CEM solution was added to Z7012C. The resistance value per 1 mm of the silver plating was 1Ω.

  From this, it was confirmed that silver plating can be formed even at room temperature by irradiating ultraviolet rays by adding a substance containing carbazole to the photocurable resin.

  Next, the metal reduction mechanism of carbazole will be examined. Carbazole is a substance having a structure as shown in FIG. 16, and the five-membered ring nitrogen portion is very easy to emit electrons, and the donor portion and Become.

  Therefore, when a group (acceptor part) that easily pulls electrons from the nitrogen of the benzene ring to the diagonal position is introduced, the electrons easily move from the donor part to the acceptor part, and the moved electrons move freely in the molecule. be able to.

  The ionization potentials of polyvinyl carbazole (PVK) and substituted polyacetylene (CzPA) having a carbazole group in the side chain are 5.9 eV and 5.6 eV, respectively. That is, by irradiating light in the near ultraviolet region (wavelength of about 210 to 220 nm), a molecule containing a carbazole group emits electrons.

Based on such characteristics of carbazole, as a mechanism of silver deposition on the modified resin to which CEM or PDA having a carbazole group in this experiment is added,
a. Silver ions are reduced and deposited by electrons emitted from carbazole when irradiated with ultraviolet rays (corresponding to ionization potential).
b. Silver ions must be present or bonded in the vicinity of carbazole (because even if electrons are released from carbazole, they are deprived of water molecules in the plating solution).
And so on.

  In other words, the silver ions are present near the carbazole group in the modified resin, and the silver ions are reduced by the electrons released from the carbazole group during ultraviolet irradiation, and the modified resin surface is silver plated. Is recognized.

  Therefore, an experiment was conducted in which silver plating was performed under the condition of not irradiating ultraviolet rays. First, the modified resin 3 in which 12% by weight of a PDA solution was added to Z7012C and Z7012C, and the CEM solution was added to 10% by weight of Z7012C. The added modified resin 4 was dropped on one glass substrate, and the droplets formed by the dropping were irradiated with ultraviolet rays and cured.

  Then, an ammoniacal silver nitrate aqueous solution in which a 0.25M silver nitrate aqueous solution and 5.5% ammonia water were mixed at a volume ratio of 10: 6 was dropped onto each of the three kinds of cured resins, and left for 24 hours in a light-shielded state.

  Thereafter, the solution is thoroughly washed with water and acetone and dried. After drying, a solution obtained by mixing the aqueous ammoniacal silver nitrate solution and the 1.9 M glucose solution used as a reducing agent in a volume ratio of 1: 1 is used for each cured resin. The solution was dropped, and silver plating was performed by electroless plating while keeping the temperature at 45 ° C.

  When the surfaces of the three types of resins that were allowed to stand for 24 hours in a light-shielded state after dropping the aqueous ammoniacal silver nitrate solution were observed, the surfaces of the modified resins to which the CEM solution was added were cloudy white. Then, when silver plating using a reducing agent was performed, silver precipitated.

  Here, the reason that the surface of the modified resin was clouded in white is considered to be because some substance adhered to the resin surface by the aqueous ammoniacal silver nitrate solution.

  Moreover, since silver has precipitated by the silver plating process using a reducing agent, it is thought that the substance adhering to this resin surface is a silver ion which exists in a certain state.

  Therefore, in the case of silver plating that performs normal ultraviolet irradiation, it can be considered that silver is precipitated by the electrons emitted from the carbazole group by the silver ions present on the resin surface.

From the experimental results of the present inventor described above, it was found that a modified resin obtained by adding an electron donor having a carbazole group to a photocurable resin was applied to the entire polymer with a resolution of about 100 nm by a two-photon absorption microfabrication method. By performing metal coating by electroless plating, a three-dimensional metal microstructure having a desired shape can be obtained.

  Furthermore, the polymer structure required by the two-photon absorption micro-molding method was intended using two types of modified resins obtained by adding a photocurable resin and an electron donor having a carbazole group to the photocurable resin. It can be localized to a part.

  Then, a three-dimensional metal microstructure having a metal microstructure selectively in the three-dimensional microstructure is produced by coating the polymer structure portion made of the modified resin with a metal by electroless plating. be able to.

The above-described embodiment can be modified as shown in the following (1) to (4).

  (1) The photocurable resin used in the present invention is not limited to those described above. For example, various photocurable resins as shown in FIG. 17 can be used.

  (2) The electron donor used in the present invention is not limited to those described above, and any electron donor can be used as long as it can eject electrons. For example, an aldehyde-based (R-CHO) as shown in FIG. Can be used as well as those having a carbazole group (all having a carbazole group in the molecule). Then, using as a connector a vinyl compound that can obtain a high molecular weight polymer by radical polymerization having a Q value close to that of the acrylic photocurable resin, an electron donor as shown in FIG. 18 is attached to this connector. When mixed in the acrylic photocurable resin, the electron donor can be successfully incorporated into the acrylic photocurable resin.

  Here, FIG. 19 shows the names and structures of typical vinyl compounds from which a high molecular weight polymer can be obtained by radical polymerization, and FIG. 20 shows the photocurable resin and the photocurable resin. The Q value of the vinyl compound serving as an index indicating the reactivity with the vinyl compound added to (added vinyl compound) is shown.

  Referring to FIG. 20, among the vinyl compounds shown in FIG. 19, styrene, acrylonitrile, methyl methacrylate and methyl acrylate not marked with x in FIG. 21 are used as connectors. It is preferable that an electron donor as shown is attached and mixed into the acrylic photocurable resin.

  Furthermore, as an electron donor used in the present invention, a semiconductor such as Si, Ga, Ge, or GaAs may be used.

  (3) In the above-described embodiment, a polymer is formed using a modified resin in which an electron donor having a carbazole group is added to the photocurable resin on a polymer structure made of a commercially available photocurable resin. Although the structure is manufactured, it is needless to say that the structure is not limited to this. That is, a polymer structure made of a photocurable resin not added with an electron donor on a polymer structure made of a modified resin obtained by adding an electron donor having a carbazole group to a photocurable resin. You may make it produce. That is, the production of the polymer structure with the photocurable resin to which no electron donor is added and the production of the polymer structure with the modified resin may be performed in any order.

  (4) You may make it combine suitably the embodiment shown above and the modification shown in said (1)-(3).

  The present invention can be used for the manufacture of microstructured electronic devices and microstructured optical devices.

FIGS. 1A, 1B, and 1C are explanatory views showing a processing procedure of a two-photon absorption fine modeling method in the case of producing a three-dimensional model of a cow having a length of 8 μm. FIGS. 2A and 2B are explanatory diagrams of a system for performing a two-photon absorption fine modeling method by irradiating a short pulse laser beam, and FIG. 2A is an overall configuration diagram. FIG.2 (b) is a side view of the dotted-line part in Fig.2 (a). FIG. 3 is a flowchart showing the processing steps of an example of the embodiment of the method for manufacturing a three-dimensional metal microstructure according to the present invention. FIG. 4 is a structural formula of polydiacetylene mixed in the photocurable resin in the experiment by the present inventors. FIG. 5 is a graph showing an absorption spectrum of a polydiacetylene solution. FIG. 6 is a CCD image of the crystallized polydiacetylene solution. FIG. 7 is an SEM image of a three-dimensional polymer structure produced by a two-photon absorption microfabrication process using a modified resin added with 16% by weight of a polydiacetylene solution. FIGS. 8A, 8B, and 8C show the surface of a modified resin to which 16% by weight of polydiacetylene is added in an electroless plating process that does not use a reducing agent. FIG. FIG. 8B is a reflected electron beam image obtained by a reflection type polarization microscope, and FIG. 8C is a silver mapping image obtained by an energy dispersive X-ray analyzer. 9 (a) and 9 (b) are SEM images showing a state in which a polymer structure is coated with silver using a modified resin to which polydiacetylene is added by the method for producing a three-dimensional metal microstructure according to the present invention. 9 (a) is an SEM image showing a state observed from directly above the polymer structure, and FIG. 9 (b) is an SEM image showing a state observed from a position inclined by 40 ° from FIG. 9 (a). . FIGS. 10A and 10B show a state in which silver is selectively coated in the same polymer structure using two types of photocurable resins by the method for producing a three-dimensional metal microstructure according to the present invention. FIG. 10 (a) is an SEM image of the entire polymer structure, and FIG. 10 (b) is an SEM image of a 1 μm diameter ring coated with silver of the polymer structure. FIG. 11 shows an example in which a large number of metal microstructures are arranged in a three-dimensional space without contacting each other by the method for manufacturing a three-dimensional metal microstructure according to the present invention. FIG. 12 is a structural formula of polydiacetylene containing no carbazole group in the side chain added to the photocurable resin. FIG. 13 is a structural formula of carbazole ethyl methacrylate that contains a carbazole group added to the photocurable resin and does not have diacetylene as a basic skeleton. FIG. 14 is a photograph showing a result of silver coating performed on the modified resin to which the substance shown in FIG. 13 is added by an electroless plating process. FIG. 15 is a photograph showing the result of silver coating performed on the two types of modified resins added with the substances shown in FIG. 13 by a plating process in which the heating time is shortened in the electroless plating process. FIG. 16 is a structural formula of carbazole. FIG. 17 is a chart showing types of photocurable resins. FIG. 18 is a chart showing the types of electron donors. FIG. 19 is a chart showing the names and structures of typical vinyl compounds from which high molecular weight polymers can be obtained by radical polymerization. FIG. 20 is a chart showing a Q value of a vinyl compound serving as an index indicating the reactivity between the photocurable resin and the vinyl compound (added vinyl compound) added to the photocurable resin. FIG. 21 is a chart showing an appropriate connector structure.

Explanation of symbols

12 Polymer structure 14 Metal microstructure 16 Glass substrate

Claims (7)

In a method for manufacturing a three-dimensional metal microstructure having an arbitrary three-dimensional shape,
A modified resin prepared by adding an electron donor that emits electrons by irradiating light to a photo-curable resin is provided with a three-dimensional microstructure by two-photon absorption fine modeling by irradiating a short pulse laser beam. A first step of forming a polymer structure;
And a second step of forming a metal film on the surface of the polymer structure by performing electroless plating on the polymer structure formed in the first step. Manufacturing method. In a method for manufacturing a three-dimensional metal microstructure having an arbitrary three-dimensional shape,
A process of forming a first polymer structure having a three-dimensional microstructure by irradiating a photocurable resin with a short pulse laser beam by a two-photon absorption fine molding method, and emitting electrons by irradiating light Of forming a second polymer structure having a three-dimensional microstructure by two-photon absorption fine modeling by irradiating a modified resin obtained by adding an electron donor to a photocurable resin with a short pulse laser beam And a first step of forming a third polymer structure comprising the first polymer structure and the second polymer structure;
A second step of performing electroless plating on the third polymer structure formed by the first step and selectively forming a metal film on the surface of the second polymer structure. A method for producing a characteristic three-dimensional metal microstructure. In the manufacturing method of the three-dimensional metal microstructure according to any one of claims 1 and 2,
The electron donor has at least one carbazole group in the molecular structure. A method for producing a three-dimensional metal microstructure. In the manufacturing method of the three-dimensional metal microstructure according to claim 3,
The electron donor is a polymer of 1,6-di (N-carbazole) -2,4-hexazine. A method for producing a three-dimensional metal microstructure, characterized in that: In the manufacturing method of the three-dimensional metal microstructure according to claim 3,
The electron donor is a polymer of 9H-carbazole-9-ethyl methacrylate. A method for producing a three-dimensional metal microstructure, wherein the electron donor is a polymer of 9H-carbazole-9-ethyl methacrylate. In the manufacturing method of the three-dimensional metal microstructure according to any one of claims 1 and 2,
The said electron donor has R-CHO in a molecular structure. The manufacturing method of the three-dimensional metal microstructure characterized by the above-mentioned. In the manufacturing method of the three-dimensional metal microstructure according to any one of claims 1 and 2,
The method for producing a three-dimensional metal microstructure, wherein the electron donor is a semiconductor.