JP2005134873A - Method for forming bell-shaped projection structure on surface of photosensitive polymer film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a bell-shaped projection structure by which a bell-shaped production structure can be easily formed on a polymer film even when the polymer film has a large surface area by an easy method of interference exposure via no mask without rotating the position of the polymer film or without rotating the direction of interference exposure. <P>SOLUTION: The method for forming a bell-shaped projection structure on the surface of a photosensitive polymer film 3 aims to form a bell-shaped projection structure on the surface of a polymer film 3 having a photosensitive function. A bell-shaped production structure is formed from a surface relief grating structure produced by subjecting the surface of a polymer film 3 having a photosensitive function to interference exposure via no mask to pulse laser light 4a, 4b in a wavelength region inducing the photosensitive function in the polymer film, without rotating the position of the polymer film 3 or without rotating the direction of interference exposure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention belongs to a technical field related to micro / nano processing of a polymer material using light, and the surface of the polymer film having a photosensitive function is subjected to interference exposure with a pulse laser beam to thereby form the surface of the polymer film The present invention relates to a method for forming a bell-shaped convex structure.

  Examples of micro / nano processing technology for polymer materials using light (processing technology on the order of micro / nanometers) include, for example, imparting photosensitivity to polymer materials themselves and irradiating light in the ultraviolet and visible wavelength regions. Typical examples include lithography performed by this method, and ablation or formation of a refractive index modulation structure using an ultrashort pulse laser or radiation light whose irradiation light has high energy. Among the micro / nano processing technologies in these polymer materials, by irradiating the surface of the photosensitive polymer film containing a material that exhibits a photoisomerization function such as azobenzene so as to cause interference exposure. A technique for forming a periodic concavo-convex structure by interference fringes was reported in 1995, and since then, the formed periodic concavo-convex structure is similar to a periodic corrugated grating, so that the surface relief This is called “Surface Relief Grating” (sometimes abbreviated as “SRG”), which is of interest to many researchers, understands the relationship between irradiation conditions and the structure to be formed, analyzes the structure formation mechanism, and forms Many studies have been made such as application studies of SRG.

The research so far mainly uses high molecular weight materials having an azobenzene derivative having an absorption peak of π-π ^* (pistar) absorption at 400 to 500 nm as a side chain, and usually has a thickness of about 1 μm or more. A molecular film is formed on a substrate such as glass, and a cw (continuous) Ar laser having a wavelength of 488 nm is irradiated on the surface of the polymer film with ^two light beams at a relatively weak power density of about several tens mW / cm ^2. Thus, by performing interference exposure, an induction structure portion (SRG structure portion) having SRG is formed.

  The lattice spacing (Λ) of the structure having the SRG structure formed by the two-beam interference exposure is expressed by the irradiation wavelength (λ), the incident angle (angle from the normal line) (θ) to the polymer film surface, and “ [Lambda] = [lambda] / 2sin [theta] ", and in order to reduce the lattice spacing ([Lambda]), it is necessary to shorten the irradiation wavelength ([lambda]) and increase the incident angle ([theta]). Since (λ) has a restriction that a wavelength in a wavelength region suitable for causing photoisomerization must be used, usually, the incident angle (θ) is set as large as possible, and the lattice spacing (Λ) is set to be as large as possible. It is small. In addition, when the obtained SRG is used as a reflection diffraction grating, in order to obtain a reflection diffraction grating having high diffraction efficiency, the height of the grating [the height of the peak to the bottom of the valley (the height of the peak to the valley) ))] Needs to be increased. For this purpose, a device has been devised to increase the irradiation energy (light intensity × irradiation time) of the light for interference exposure or to increase the thickness of the polymer film.

The knowledge about SRG that has been clarified through previous studies can be listed as in the following (1) to (7) (see Non-Patent Document 1).
(1) The brightness and darkness of the interference fringes formed by interference exposure corresponds to the valley portions of the SRG (the SRG has a phase relationship of π shift with the interference fringes). That is, mass transfer occurs from a bright part where the light intensity is increased by interference to a dark part, and an SRG is formed.
(2) SRG can be formed in a temperature region lower than the glass transition temperature (Tg) of the polymer material forming the film. That is, under the temperature range in which mobility is inherently low (lower than the Tg of the polymer material and macroscopically in the glassy temperature range), mass transfer with microscopic flow occurs and SRG is formed. The
(3) The height of the SRG peak-valley region (the peak peak-valley peak) increases initially in proportion to the energy of the irradiation light (light intensity × irradiation time), but the thickness of the polymer film And saturates at a certain irradiation energy.
(4) The formation of SRG strongly depends on the polarization state of the irradiation light, and in the linearly polarized irradiation light, the p-polarization occurs more efficiently than the s-polarization.
(5) The higher the molecular weight of the polymer used, the lower the efficiency of SRG formation. This is because the degree of polymer entanglement affects the mass transfer.
(6) The formed SRG can be overwritten, and the existing SRG pattern is preserved as it is even during additional recording.
(7) The formed SRG can be erased by heating above the Tg of the polymer material used or by performing uniform light irradiation under appropriate polarization conditions.

  As for the formation mechanism of the SRG structure, the local free volume change based on photoisomerization forms a pressure distribution inside the film, and as a result, mass transfer occurs and SRG is formed by π shift. Although a volume model was proposed (see Non-Patent Document 2), the polarization dependence in SRG formation could not be well explained. On the other hand, the light gradient force due to the force from the optically induced electric field acts on the dipole of the polymer chain, brings about a moving force in the polymer material, and the light that forms the SRG structure. A gradient force model has been proposed, and the polarization dependence can be explained (see Non-Patent Document 3). A Viscous Mass Flow model was also proposed, and an experiment in which the SRG formation rate is proportional to the cube of the film thickness at a film thickness of 1 μm or less, assuming that the mass transfer rate decreases from the surface in the depth direction. The results were explained (see Non-Patent Document 4). In addition, as another model, in a system including a liquid crystal material, an SRG is formed without a shift (zero shift) instead of a π shift. A Mean Field Theory model (see Non-Patent Document 5) that can explain the SRG is formed. A diffusion model (see Non-Patent Document 6) has been proposed that focuses on the fact that the surface effect is governed by the diffusion of molecules and the time scale of the orientation distribution is much shorter than the time scale of diffusion.

  The SRG structure does not require complicated development processes or chemical treatments like lithography, and can be processed, recorded and erased in a single stage of light irradiation, and can be reversibly formed repeatedly. It has certain characteristics. As its application, rewritable hologram material can be expected to be applied to 2D and 3D information recording / computing media. Studies such as dynamic holography that can form an SRG in a short time of about 5 nanoseconds and can be erased by heat treatment have been conducted. In addition, the use of a replica structure as an optical printing using the SRG structure as a phase mask is also being studied. In addition, studies on the extraction of light such as optical filters and optical couplers as diffraction gratings, optical functional elements for waveguides, and research on alignment films for liquid crystals have been actively conducted. Furthermore, the use of the SRG structure to improve the strength of the polymer film, and the use of the SRG structure as a photo-electric device or a second harmonic oscillator by corona discharge are being studied. Yes.

  The above description relates to the SRG structure in which the periodic concavo-convex structure formed by interference exposure is similar to the grating having a periodic waveform shape. There are two photo-induced surface structures by interference exposure. One is a honeycomb structure close to a hexagonal crystal formed by irradiating a three-beam laser beam having appropriate polarization characteristics, and the other is a first stage in two-beam interference exposure for a predetermined time. The SRG structure is formed by two-beam interference exposure, and then the polymer film sample is rotated by 90 degrees, or the polymer film sample is left as it is and the two-beam interference direction is rotated by 90 degrees. The SRG (SRG formed by the first-stage two-beam interference exposure) is overwritten with an SRG that is orthogonally written to form a bell-shaped structure (egg-crate-like structure; egg pack-shaped structure: “ECL”) May be abbreviated as “structure”). Since these two structures are surface-induced structures having higher order regularity than the lattice-like SRG structure, they are widely used such as macro lens arrays, diffusion plates, and photonic crystals. Use as an optical functional material is expected.

  In particular, the bell-shaped structure (ECL structure) is a so-called microlens array-like structure, in which a substrate is immersed in a fine particle dispersion in which fine particles of nanometer order or micrometer order with uniform particle diameter are dispersed, A structure obtained by pulling up to form a uniform single layer on a substrate, or forming a ferroelectric polymer LB film on a graphite substrate, and performing a scanning tunneling microscope operation under a high vacuum / electric field application condition, A structure obtained by inducing polymer rearrangement, a structure obtained by exposing and curing a photoresist with ultraviolet light (UV light) through a photomask, and a selective (different) crystal plane of the silicon substrate. It has a regular structure that is very similar to a structure obtained by etching. Compared to these similar structure fabrication methods, the fabrication method of the induction structure (bell-shaped convex structure) having a bell-shaped convex structure (bell-shaped structure) by interference exposure is strict in terms of process. It can be said that it is a bell-shaped structure by a simple manufacturing method, but it is necessary to form an orthogonal SRG by two-stage two-beam interference exposure, and a polymer between the first stage and the second stage. It is necessary to rotate the film sample or the two-beam interference direction by 90 degrees. Therefore, a two-stage two-beam interference exposure method in which the SRG formed by the second-stage two-beam interference exposure is orthogonal to the SRG formed by the first-stage two-beam interference exposure formed in a minute area. Uses a lot of alignment, especially when creating a bell-shaped structure on the surface of a large area, a bell-shaped structure is created on the surface of a small area, and they are combined to increase the area So it will take more time and effort.

  As for SRG, a method for producing a diffraction grating by irradiating a polymer layer having an azobenzene skeleton twice with a laser (see Patent Document 1), a photosensitive material containing a polymer substance having an azobenzene skeleton and a liquid crystal substance. A pattern formed on a thin film by pattern exposure to a thin film made of a conductive composition (see Patent Document 2), the surface of an azobenzene polymer film is irradiated with object light and reference light, and intensity distribution due to interference between the two Is written as SRG, and a hologram is produced (see Patent Document 3), an unevenness functioning as a lenticular lens is formed on the surface of the azo polymer carrier, and a fine unevenness is formed on the surface of the unevenness (see Patent Document 4). ) Interference with a photosensitive thin film composed of a specific azobenzene derivative through a mask having a predetermined pattern By performing light has also been proposed a method of forming a relief (see Patent Document 5).

  However, even in these methods, the position of the polymer film is rotated, the direction of interference exposure is rotated, or a mask is used. The rotation of the position of the polymer film is not performed without using a mask. A bell-shaped structure (bell-shaped convex structure) is easily formed on the polymer film by a simple method without rotating in the direction of interference exposure, and even if the surface area of the polymer film is large There is a need for a method that can do this.

International Publication No. 98/36298 Pamphlet JP 2002-105339 A JP 2002-182547 A Japanese Patent Laid-Open No. 2002-147331 JP 2003-82033 A

“O plus E”, New Technology Communications Publishing, March 2003, Vol. 24, p. 287 “J. Phys. Chem.” 1996, Vol. 100, p. 8836 “Appl. Phys. Lett.” 1998, Vol. 72, p. 2096 “Mol. Crys. Liq. Crys.” 2000, Vol. 345, p. 263 “Phys. Rev. Lett.” 1998, 80, p. 89 “Opt. Mater.” 1998, Vol. 9, p. 323

  Therefore, an object of the present invention is to perform interference exposure without using a mask, and to increase the surface area of the polymer film by a simple method without rotating the position of the polymer film or the direction of interference exposure. To provide a method for forming a bell-shaped convex structure portion on the surface of a photosensitive polymer film, which can easily form a bell-shaped structure portion (bell-shaped convex structure portion) on the polymer film. It is in.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have found that when the surface of the photosensitive polymer film is subjected to interference exposure with a specific pulse laser beam without using a mask, the photosensitive polymer film It has been found that a bell-shaped convex structure can be easily formed on the surface of the photosensitive polymer film via the surface relief grating structure without rotating the position or rotating in the direction of interference exposure. It was. The present invention has been completed based on these findings.

  That is, the present invention relates to a method for forming a bell-shaped convex structure on the surface of a polymer film having a photosensitive function, wherein the polymer film is exposed to the surface of the polymer film having a photosensitive function. A bell-shaped convex structure having a bell-shaped convex structure formed via a surface relief grating structure by performing interference exposure of a pulsed laser beam in a wavelength region that exhibits sexual functions without passing through a mask A method for forming a bell-shaped convex structure on the surface of a photosensitive polymer film, wherein the part is formed without rotating the position of the polymer film or rotating in the direction of interference exposure. .

  As the polymer film having a photosensitive function, a polymer film that can exhibit a photosensitive function by photoisomerization, photorefractive property, photocrosslinking property or photodegradability can be preferably used, and a side chain can be used. It is preferably formed of a polymer having a group or moiety containing an azobenzene skeleton. As the polymer component having a side chain containing the azobenzene derivative portion, a polymer component of an azobenzene dye having at least two hydroxyl groups and a monomer component having at least two reactive functional groups for the hydroxyl group in the azobenzene dye is used. It may be a coalescence.

  In addition, the thickness of the polymer film is preferably 100 nanometers (nm) or more. The height of the bell-shaped convex structure may be 80 nanometers (nm) or more.

Further, as the pulse laser beam, a pulse laser beam and a pulse laser beam having a pulse width of 500 μsec or less are suitable. The pulse laser beam may have a light intensity of 10 mW / cm ^{2 to 1} W / cm ² and preferably has p-polarization polarization characteristics or circular polarization characteristics.

  In the present invention, the bell-shaped convex structure formed on the surface of the polymer film having the photosensitive function can exhibit a light collecting function with respect to light incident from the back surface of the polymer film. Is preferred.

  According to the method for forming a bell-shaped convex structure on the surface of the photosensitive polymer film of the present invention, interference exposure is performed without using a mask, and the position of the polymer film and the direction of interference exposure are rotated. A bell-shaped convex structure can be easily formed on the polymer film by a simple method without performing it, and even if the surface area of the polymer film is large.

(Photosensitive polymer film)
In the present invention, the photosensitive polymer film used for forming the bell-shaped convex structure is formed of a polymer having a photosensitive function (sometimes referred to as “photosensitive polymer”). It is a membrane. Such a photosensitive polymer is not particularly limited as long as it has a group or moiety that exhibits a photosensitive function. For example, a polymer having a group or moiety containing an azobenzene skeleton in the molecule (“azobenzene”). (Sometimes referred to as “skeleton-containing polymer”). That is, the group or site | part containing an azobenzene skeleton is utilized as a group or site | part which exhibits a photosensitive function. A photosensitive polymer can be used individually or in combination of 2 or more types.

  The azobenzene skeleton-containing polymer may have at least one group or moiety containing an azobenzene skeleton in the molecule, for example, a group or moiety containing an azobenzene skeleton in the main chain or side chain. Examples include polymers. As the azobenzene skeleton-containing polymer, a polymer having a group or moiety containing an azobenzene skeleton in the side chain (polymer component having a side chain containing an azobenzene derivative portion) is suitable.

  In a polymer having a group or moiety containing an azobenzene skeleton in the side chain (sometimes referred to as “azobenzene skeleton side chain-containing polymer”), the group or moiety containing the azobenzene skeleton is included in all side chains. It may be included in only some side chains. Furthermore, the azobenzene skeleton side chain-containing polymer may have a group or moiety containing one azobenzene skeleton in one side chain, or a group or moiety containing two or more azobenzene skeletons. May be.

（式（１）において、Ｒ¹、Ｒ²は、同一又は異なって、２価の炭化水素基を示す。Ｒ³は有機基を示す。また、Ｒ⁴は２価の有機基であり、ｎは０又は１である） In the azobenzene skeleton side chain-containing polymer, the azobenzene skeleton is not particularly limited as long as it is a group or moiety having a “phenylene-azo-phenylene (—C ₆ H ₄ —N═N—C ₆ H ₄ —)” group. First, a group or a moiety composed of various azobenzene derivatives can be used. As the azobenzene skeleton side chain-containing polymer, for example, a functional group bonded to the main chain or the side chain is reacted with a compound having an azobenzene skeleton together with a group reactive to the functional group. Thus, a polymer in a form in which a group or moiety containing an azobenzene skeleton is introduced into the side chain, or a monomer component having a group or moiety containing an azobenzene skeleton as a monomer component (sometimes referred to as “azobenzene skeleton-containing monomer component”) ), A polymer having a form in which a group or moiety containing an azobenzene skeleton is introduced in the side chain can be used. In the present invention, as the azobenzene skeleton side chain-containing polymer, a polymer prepared using an azobenzene skeleton-containing monomer component can be suitably used. The azobenzene skeleton-containing monomer components can be used alone or in combination of two or more. Such an azobenzene skeleton-containing monomer component is appropriately selected depending on the type of polymerization form of the main chain [eg, polymerization forms such as polycondensation (condensation polymerization), addition polymerization, polyaddition, addition condensation, ring-opening polymerization, oxidation polymerization, etc.]. You can choose. For example, when the polymerization form of the main chain is condensation polymerization involving a hydroxyl group, an azobenzene skeleton-containing monomer component represented by the following formula (1) can be suitably used as the azobenzene skeleton-containing monomer component.

(In the formula (1), R ¹ and R ² are the same or different and represent a divalent hydrocarbon group. R ³ represents an organic group. R ⁴ represents a divalent organic group. Is 0 or 1)

In the formula (1), R ¹ and R ² are divalent hydrocarbon groups. Examples of the divalent hydrocarbon group include an alkylene group (methylene group, ethylene group, trimethylene group, propylene group, tetramethylene group, pentamethylene group, hexamethylene group, etc.), cycloalkylene group (cyclohexylene group, etc.). , Arylene groups (phenylene groups, naphthylene groups, etc.), or groups obtained by combining these groups. R ¹ and R ² may be the same or different. R ¹ and R ² are preferably both the same alkylene group (particularly an ethylene group).

R ³ is an organic group. The organic group is not particularly limited as long as it is a monovalent organic group. For example, nitro group, cyano group, isocyanate group, amino group, heterocyclic group-containing group, hydroxyl group, epoxy group, substituted oxy group (alkoxy group) Cycloalkyloxy group, aryloxy group, etc.), substituted oxycarbonyl group (alkoxycarbonyl group, cycloalkyloxycarbonyl group, aryloxycarbonyl group etc.), carboxyl group, acyl group, acyloxy group, hydrocarbon group (alkyl group, Cycloalkyl group, aryl group, etc.), mercapto group, sulfo group and the like. R ³ is preferably a group containing a nitrogen atom (nitro group, cyano group, isocyanate group, etc.), and nitro group is particularly preferable.

R ³ represents any part of the benzene ring on the terminal side in the azobenzene skeleton [any part of the 2-position (o-position, 3-position (m-position), 4-position (p-position)]]. It is preferable that it is bonded to the 4-position (p-position).

R ⁴ is a divalent organic group. Examples of the divalent organic group include divalent hydrocarbon groups such as alkylene groups, cycloalkylene groups, and arylene groups, divalent hydrocarbon groups, and other groups (for example, oxygen atom-containing groups, nitrogen Groups containing a combination of an atom-containing group and a sulfur atom-containing group). N is 0 or 1, and when n is 0, it means that R ⁴ is not present and the azobenzene skeleton is directly bonded to the nitrogen atom. n is preferably 0.

  Therefore, 4- (N, N-dihydroxyethylamino) -4′-nitroazobenzene can be suitably used as the azobenzene skeleton-containing monomer component represented by the formula (1).

  The azobenzene skeleton-containing monomer component represented by the formula (1) can be classified as an azobenzene dye having at least two hydroxyl groups.

（式（２）において、Ｘは２価の有機基である。Ｒ⁵、Ｒ⁶は、同一又は異なって、ヒドロキシル基に対して反応性を有する基を示す） When the azobenzene skeleton-containing monomer component represented by the formula (1) is used as the monomer component, the azobenzene skeleton-containing monomer component represented by the formula (1) is reactive with the azobenzene skeleton-containing monomer component. It is important to use a monomer component that has (sometimes referred to as a “reactive monomer component”). In addition, a reactive monomer component can be used individually or in combination of 2 or more types. As the reactive monomer component, since the azobenzene skeleton-containing monomer component represented by the formula (1) has two hydroxyl groups (hydroxyl groups) in the molecule, the reactive functional group (hydroxyl group) for the hydroxyl group A reactive monomer component having at least two reactive functional groups) can be used. As such a reactive monomer component, a reactive monomer component represented by the following formula (2) can be suitably used.

(In Formula (2), X is a divalent organic group. R ⁵ and R ⁶ are the same or different and each represents a group reactive to a hydroxyl group.)

In the formula (2), X is a divalent organic group and serves as a skeleton of the reactive monomer component represented by the formula (2). R ⁵ and R ⁶ are groups reactive to hydroxyl groups (hydroxyl group-reactive functional groups), and the reactive monomer component represented by the formula (2) has two hydroxyl group reactions. It has a functional group. On the other hand, the azobenzene skeleton-containing monomer component represented by the formula (1) has two hydroxyl groups as represented by the formula (1). Therefore, the azobenzene skeleton-containing monomer component represented by the formula (1) and the reactive monomer component represented by the formula (2) can be subjected to condensation polymerization.

  The divalent organic group in X is not particularly limited as long as it is a divalent organic group. For example, it is a divalent hydrocarbon group, a divalent heterocyclic group, a divalent hydrocarbon group or a divalent group. And a group obtained by combining the above heterocyclic group with another group (for example, an oxygen atom-containing group, a nitrogen atom-containing group, a sulfur atom-containing group, etc.). Examples of the divalent hydrocarbon group include a divalent aliphatic hydrocarbon group such as an alkylene group, a divalent alicyclic hydrocarbon group such as a cycloalkylene group, and a divalent aromatic hydrocarbon such as an arylene group. Groups and the like. In the divalent aliphatic hydrocarbon group, the alkylene group includes, for example, a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, and a branched chain. And an alkylene group (for example, a propylene group). In the divalent alicyclic hydrocarbon group, examples of the cycloalkylene group include cyclohexylene, cycloheptylene, and cyclooctylene groups. In the divalent aromatic hydrocarbon group, the arylene group includes a phenylene group (for example, a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, etc.), a naphthylene group, and the like. .

  In the divalent heterocyclic group, the heterocyclic ring includes, for example, a heterocyclic ring containing a nitrogen atom as a hetero atom (for example, a 5-membered ring such as pyrrole, pyrazole, imidazole, triazole, pyridine, pyridazine, pyrimidine, pyrazine, etc. 6-membered rings, condensed rings such as indole, quinoline, acridine, naphthyridine, quinazoline, and purine), heterocycles containing an oxygen atom as a hetero atom (for example, 5-membered rings such as furan, oxazole, isoxazole, 4-oxo, etc. 6-membered rings such as -4H-pyran, condensed rings such as benzofuran, isobenzofuran and 4-oxo-4H-chromene), and heterocycles containing a sulfur atom as a heteroatom (for example, thiophene, thiazole, isothiazole, thiadiazole, etc.) 5-membered ring, 4-oxo-4H-thiopyran, etc. 6-membered rings, fused rings such as benzothiophene), and the like. In these heterocycles, the two bonding positions are not particularly limited.

  X may have various substituents as long as the reactivity between the hydroxyl group in the formula (1) and the hydroxyl group-reactive functional group in the formula (2) is not impaired. Examples of such substituents include hydrocarbon groups (methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, s-butyl groups, t-butyl groups and other alkyl groups; cyclohexyl groups, etc. Cycloalkyl group; aryl group such as phenyl group), substituted oxy group (alkoxy group such as methoxy group, ethoxy group, propoxy group, isopropoxy group, cycloalkyloxy group, aryloxy group, etc.), substituted oxycarbonyl Groups (alkoxycarbonyl group, cycloalkyloxycarbonyl group, aryloxycarbonyl group, etc.) and the like.

  As the divalent organic group for X, a divalent hydrocarbon group is preferable, and a divalent aromatic hydrocarbon group (particularly a tolylene group) is particularly preferable.

R ⁵ and R ⁶ are hydroxyl group-reactive functional groups. The hydroxyl group-reactive functional group is not particularly limited as long as it is a group reactive to a hydroxyl group, and examples thereof include an isocyanate group, a carboxyl group, an epoxy group, an amino group, and a mercapto group. R ⁵ and R ⁶ are preferably isocyanate groups. R ⁵ and R ⁶ may be the same or different.

  Accordingly, examples of the reactive monomer component represented by the formula (2) include a diisocyanate monomer component, a dicarboxylic acid monomer component, a diepoxy monomer component, a diamine monomer component, and a dithiol monomer component. As the reactive monomer component represented by the formula (2), a diisocyanate monomer component is preferable.

  Specifically, in the reactive monomer component represented by the formula (2), 1,6-hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate are used as the diisocyanate monomer component. Aliphatic diisocyanates such as 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate; isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated tri Alicyclic diisocyanates such as diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate; 2,4-tolylene diisocyanate Neat (tolylene-2,4-diisocyanate), 2,6-tolylene diisocyanate 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m -Phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'- Aromatic diisocyanates such as diisocyanates; aromatic aliphatic diies such as xylylene-1,4-diisocyanates, xylylene-1,3-diisocyanates Cyanate - such as theft and the like. As the diisocyanate monomer component, 2,4-tolylene diisocyanate can be suitably used.

  In the reactive monomer component represented by the formula (2), examples of the dicarboxylic acid monomer component include succinic acid, methyl succinic acid, adipic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, Aliphatic dicarboxylic acids such as 1,14-tetradecanedioic acid and dimer acid; aromatic dicarboxylic acids such as phthalic acid, 1,4-naphthalenedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid. Further, as the dicarboxylic acid monomer component, the above-mentioned reactive derivatives of dicarboxylic acid (acid anhydride, lower alkyl ester, etc.) can also be used. The diepoxy monomer component, the diamine monomer component, and the dithiol monomer component are respectively known diepoxy monomer components (for example, epoxy resins such as biphenyl type epoxy resins and bisphenol A type epoxy resins) and known diamines. A monomer component (for example, a diamine compound such as ethylenediamine, 1,6-hexamethylenediamine, isophoronediamine, 2,4-tolylenediamine, etc.) or a known dithiol monomer component may be appropriately selected and used. it can.

  In the present invention, when the azobenzene skeleton-containing monomer component represented by the formula (1) is used as the monomer component, the azobenzene skeleton-containing monomer component represented by the formula (1) and the azobenzene skeleton-containing monomer component are used. In addition to the reactive monomer component (reactive monomer component), if necessary, other than the azobenzene skeleton-containing monomer component having reactivity with the reactive monomer component and represented by the formula (1) Monomer components (sometimes referred to as “reactive functional monomer components”) can be used. In addition, as a reactive functional monomer component, it can be used individually or in combination of 2 or more types. Such a reactive functional monomer component can be appropriately selected according to the type of the reactive monomer component. As the reactive functional monomer component, for example, a monomer component that does not have a group or site containing an azobenzene skeleton and contains at least two hydroxyl groups (when referred to as “hydroxyl group-containing reactive functional monomer component”) Can be suitably used. The hydroxyl group-containing reactive functional monomer component as the reactive functional monomer component is not particularly limited, and various diol components can be appropriately selected and used, for example, ethylene glycol, 1,3-trimethylene glycol, 1 , 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,18-octadecanediol, neopentyl Glycol, 2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1 , 3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanedio 2,4-diethyl-1,5-pentanediol, 1,3,5-trimethyl-1,3-pentanediol, 2-methyl-1,6-hexanediol, 2-methyl-1,8-octane Examples thereof include aliphatic diol components such as diol, 2-methyl-1,9-nonanediol, and dimer diol; alicyclic diol components such as 1,4-cyclohexanediol.

  Examples of the diol component as the hydroxyl group-containing reactive functional monomer component include polymer diol components such as polyester diol components, polyether diol components, and polycaprolactone diol components (particularly aliphatic polymer diol components). It is also possible to use. Specifically, examples of the polyester diol component include a polyester diol obtained by dehydrating a diol component such as the aliphatic diol component and a dicarboxylic acid component or a derivative thereof alone or in a mixture state. . Examples of the polyether diol component include polyethylene glycol obtained by ring-opening polymerization of ethylene oxide, propylene oxide, tetrahydrofuran and the like, polypropylene glycol, polytetramethylene glycol, and copolyether obtained by copolymerization thereof. Examples of the polycaprolactone diol component include caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and δ-valerolactone.

  As the azobenzene skeleton side chain-containing polymer, an azobenzene skeleton side chain-containing polymer obtained by condensation polymerization using the azobenzene skeleton-containing monomer component represented by the formula (1) can be preferably used. The azobenzene skeleton side chain-containing polymer obtained by condensation polymerization of the azobenzene skeleton-containing monomer component represented by the formula (1) and the reactive monomer component represented by the formula (2) is preferred. That is, as the azobenzene skeleton side chain-containing polymer, a polymer (polymer) of an azobenzene dye having at least two hydroxyl groups and a monomer component having at least two reactive functional groups with respect to hydroxyl groups is preferably used. Can do.

  Of course, in the azobenzene skeleton side chain-containing polymer, the main chain is formed by polymerization by a polymerization form other than condensation polymerization (addition polymerization, polyaddition, addition condensation, ring-opening polymerization, oxidation polymerization, etc.). Even if it exists, it can be used. For example, when the main chain is formed by addition polymerization, the monomer component for preparing the azobenzene skeleton side chain-containing polymer includes, for example, a group or moiety containing an azobenzene skeleton, A monomer component having a saturated bond can be used. In this case, if necessary, a monomer component that does not have a group or moiety containing an azobenzene skeleton and has an ethylenically unsaturated bond can be used.

  The photosensitive polymer film is formed of a photosensitive polymer, and the formation method (film formation method) is not particularly limited, and a known or commonly used polymer material film formation method or lamination method can be used. . More specifically, examples of the method for forming a photosensitive polymer film include a method in which a photosensitive polymer is dissolved or dispersed in a solvent or a matrix, and casting, spin coating, or the like is performed. The solvent or matrix for dissolving or dispersing the photosensitive polymer is not particularly limited and can be appropriately selected depending on the type of the photosensitive polymer. Examples of the solvent include amides such as formamide, acetamide, dimethylformamide (DMF) and dimethylacetamide (DMAc); nitriles such as acetonitrile, propionitrile and benzonitrile; nitro compounds such as nitrobenzene, nitromethane and nitroethane; chloroform Various solvents such as halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, chlorobenzene, and trifluoromethylbenzene can be appropriately selected and used.

  In addition, it is preferable to filter the solution which dissolve | melted the photosensitive polymer in the solvent using a filter paper, a filter for filtration, etc., and to remove the impurity, dust, etc. before forming into a film.

  Specifically, the photosensitive polymer is dissolved in a solvent such as N, N-dimethylacetamide (DMAc) to prepare a 0.16 wt% solution, and the solution is placed on a predetermined substrate at 70 ° C. The photosensitive polymer film can be produced by casting with the above method. Note that the photosensitive polymer film may be formed on a substrate as described above, and as such a substrate, various substrates (glass substrate, plastic substrate, etc.) are appropriately selected and used. Can do. When forming a photosensitive polymer film on a substrate, before forming the film, the surface of each substrate is cleaned of impurities, dust, etc. adhering to the surface using ultrasonic waves or fluid. It is desirable to remove and wash.

  In the present invention, pre-treatment such as filtration of a solution in which a photosensitive polymer is dissolved in a solvent and cleaning of a substrate are performed by subjecting a polymer film placed on the substrate to interference exposure with pulsed laser light, and a bell-shaped convex shape. This is effective in avoiding the formation of a non-uniform induced structure starting from impurities and dust when forming the structure portion.

  The thickness of the photosensitive polymer film is not particularly limited, and can be selected, for example, from a range of 0.1 μm (100 nm) or more (for example, about 0.1 to 50 μm. The thickness of the photosensitive polymer film) Is preferably 0.3 μm (300 nm) or more (for example, 0.3 to 30 μm), more preferably 0.5 μm (500 nm) or more (for example, 0.5 to 20 μm). As the photosensitive polymer film, those having a thickness of 0.5 to 1 μm are particularly suitable.If the thickness of the photosensitive polymer film is too thin, the formation of a bell-shaped convex structure portion by pulsed laser light is preferable. Care must be taken as this may have an impact.

  The photosensitive polymer film may have any structure of a single layer and a multilayer. The photosensitive polymer film may appropriately contain other materials and additives as necessary.

  The upper surface of the photosensitive polymer film is preferably a flat surface, but may have an uneven shape. Further, the size (area) of the upper surface is not particularly limited.

  As the photosensitive polymer that forms the photosensitive polymer film, for example, when a polymer having a group or a part including an azobenzene skeleton in the side chain is used, the azobenzene skeleton is included by interference exposure with pulsed laser light. The photosensitivity function can be exhibited when the group or site undergoes photoisomerization from the trans form to the cis form. Of course, in the present invention, as the photosensitive polymer film, a photosensitive polymer film capable of exhibiting a photosensitive function other than photoisomerization may be used, for example, photorefractive property, photocrosslinking property, light A photosensitive polymer film that can exhibit a photosensitive function by degradability can be used. That is, the photosensitive polymer forming the photosensitive polymer film has photoisomerization, photorefractive property, photocrosslinking property, photodegradability, etc. as characteristics for exhibiting the photosensitive function. Is preferred. In addition, these characteristics may have only 1 type and may have 2 or more types.

(Interference exposure using pulsed laser light)
In the present invention, the surface of the photosensitive polymer film is subjected to interference exposure with pulsed laser light without using a mask. It is important that the pulsed laser beam is a pulsed laser beam in a wavelength region that allows the photosensitive polymer film to exhibit a photosensitive function. Therefore, the wavelength region of the pulsed laser light can be appropriately selected according to the type of the photosensitive polymer or the type of group or site that exhibits the photosensitive function in the photosensitive polymer. In particular, even if the wavelength of the pulsed laser light emitted from the light source is not in a wavelength region that causes the photosensitive polymer film to exhibit a photosensitive function, by utilizing a multiphoton absorption process upon irradiation with the pulsed laser light, The photosensitive polymer film can exhibit a photosensitive function. Specifically, when the pulsed laser light emitted from the light source is condensed and irradiated with the condensed pulsed laser light, multiphoton absorption (for example, two-photon absorption, three-photon absorption, four-photon absorption, Photosensitive polymer film, even if the wavelength of the pulsed laser light emitted from the light source is not in a wavelength region that causes the photosensitive polymer film to exhibit a photosensitive function. Is substantially irradiated with a pulsed laser beam in a wavelength region that causes the photosensitive polymer film to exhibit a photosensitive function. As described above, the pulsed laser beam for the interference exposure may be substantially a pulsed laser beam in a wavelength region that causes the photosensitive polymer film to exhibit the photosensitive function, and the wavelength is appropriately selected depending on the irradiation conditions. can do. That is, as the pulse laser beam, for example, when the multiphoton absorption process is not used, the pulse laser beam having a wavelength region in which the wavelength of the pulse laser beam emitted from the light source exerts a photosensitive function on the polymer film is used. When a multiphoton absorption process is used, pulse laser light having a wavelength that is an integral multiple of the wavelength that causes the polymer film to exhibit a photosensitive function can be used.

  The multiphoton absorption process means a process in which a plurality of photons are simultaneously absorbed by a substance or a state thereof when a high-density photon exists, and cannot be generated by the energy of one photon. Phenomenon can occur. In addition, since a non-linear phenomenon is used, processing that exceeds the diffraction limit of the irradiation wavelength is possible despite the use of light.

  As described above, when the multi-photon absorption process is used in the irradiation of the pulse laser beam, the condensed pulse laser beam can be used. The multiphoton absorption process can be controlled by appropriately adjusting the intensity of the pulsed laser beam and the degree of its focusing. Note that the probability of multiphoton absorption increases in proportion to the intensity of light. As the intensity increases, multiphoton absorption is more likely to occur. Further, the method for condensing the pulsed laser light is not particularly limited, and for example, a method using a condensing lens can be suitably employed. Such a condensing lens is not particularly limited, and can be appropriately selected according to the material of the photosensitive polymer film, the size of the target bell-shaped convex structure, and the like.

As the pulse laser beam, a pulse laser having a pulse width of 5 × 10 ⁻⁴ seconds (500 μsec) or less can be suitably used. If the pulse width of the pulsed laser light exceeds 5 × 10 ⁻⁴ seconds, the bell-shaped convex structure may not be formed on the surface of the photosensitive polymer film. The pulse width of the pulse laser beam is preferably 10 ⁻⁶ seconds or less (particularly 10 ⁻⁸ seconds or less). Note that the lower limit of the pulse width of the pulse laser beam is not particularly limited, and may be, for example, 10 ⁻¹⁵ seconds or more.

Specifically, examples of pulse laser light include pulse lasers and excimer lasers having a pulse width of 5 × 10 ⁻⁴ seconds or less obtained by reproducing and amplifying a laser or dye laser using a titanium / sapphire crystal as a medium. Alternatively, a pulse laser having a pulse width of 5 × 10 ⁻⁴ seconds or less using a harmonic of a YAG laser (Nd: YAG laser or the like) [for example, a second harmonic (second harmonic) or the like] can be used.

  As described above, when using the multiphoton absorption process, the wavelength of the pulse laser beam is an integral multiple (2 times, 3 times) of the absorption wavelength (absorption peak wavelength) of the photosensitive polymer of the photosensitive polymer film. On the other hand, when the multiphoton absorption process is not used, it is preferable that the wavelength be the absorption wavelength (absorption peak wavelength) of the photosensitive polymer in the photosensitive polymer film.

  The pulse laser beam may have any polarization characteristic, but preferably has linear polarization characteristics or circular polarization characteristics. Furthermore, the linear polarization characteristic in the pulse laser beam may be any of the p-polarization polarization characteristic and the s-polarization polarization characteristic, but the p-polarization polarization characteristic is preferable. Therefore, as the pulse laser beam, a linearly polarized pulse laser beam having a p-polarized polarization property or a circularly polarized pulse laser beam is preferable.

  As the pulsed laser light, for example, the photosensitive polymer forming the photosensitive polymer film is a polymer having a side chain containing a group or site containing an azobenzene skeleton (a polymer having a side chain containing an azobenzene derivative portion). Component), the second harmonic of the Nd: YAG laser and the second harmonic of the Nd: YAG laser, which is a p-polarized pulse (pulse width: 10 ns, repetition: 10 Hz) of the second harmonic (wavelength: 532 nm). A pulsed laser beam using a circularly polarized pulse (pulse width: 10 ns, repetition: 10 Hz) of harmonics (wavelength: 532 nm) can be suitably used. In the case of pulsed laser light with circular polarization characteristics, a larger number of shots is required when forming a bell-shaped convex structure when irradiated with pulsed laser light with the same irradiation light intensity as compared with pulsed laser light with linear polarization characteristics. Necessary.

  Note that the repetition of the pulsed laser light is in the range of 1 Hz to 100 MHz, usually about 10 Hz to 500 kHz.

As the pulsed laser beam of light intensity (illumination intensity), it is not particularly limited, for example, can be appropriately selected from ^{10~1000mW / cm 2 (10mW / cm} 2 ~1W / cm 2) approximately ranges. If the light intensity of the pulse laser beam is less than 10 mW / cm ² , the light intensity may be too weak to form a bell-shaped convex structure, and if it exceeds 10 to 1000 mW / cm ² , Is too strong, and damage such as ablation may occur in the photosensitive polymer film.

  In the present invention, when performing interference exposure with pulsed laser light, it is important that the position of the photosensitive polymer film is not rotated or the direction of interference exposure is not performed. That is, interference fringes with a specific pitch interval are formed by interference exposure with pulsed laser light, so that the photosensitive polymer film can be rotated without rotating the position of the photosensitive polymer film or the direction of interference exposure. It is possible to irradiate the film with pulsed laser light whose intensity continuously changes at a specific period, thereby forming a bell-shaped convex structure having a specific periodic structure.

  In such interference exposure, coherent light caused by multi-beam interference (for example, two-beam interference or interference caused by three or more beams) can be used. A bell-shaped convex structure having a specific periodic structure (particularly, a periodic structure in the order of the wavelength of the pulsed laser beam) is formed by easily controlling the target periodic structure by multi-beam interference such as two-beam interference. be able to. For example, in the case of interference exposure using two-beam interference, the interval between the periodic structures of the bell-shaped convex structure portion to be formed can be controlled by controlling the angle between the beams.

  A known interference exposure apparatus can be used for the pulsed laser beam interference exposure. Specifically, as the interference exposure of the pulse laser beam, when performing the two-beam interference exposure, for example, an apparatus having a configuration as shown in FIG. 1 can be used. FIG. 1 is a diagram showing an outline of the configuration of an apparatus used when irradiating pulsed laser light by two-beam interference exposure. FIG. 2 is a schematic view showing a situation in which the photosensitive polymer film is subjected to two-beam interference exposure using the interference exposure apparatus shown in FIG. 1 and the induced structure formed. 1 and 2, 1 is a main part of a pulse laser beam interference exposure apparatus, 2a is a light source, 2b is an ND (neutral density) filter, 2c is a λ / 2 plate (1/2 wavelength plate), and 2d is a KTP crystal. 2e is a BBO crystal, 2f is a 355 nm wavelength mirror, 2g is a 532 nm wavelength mirror, 2h is a λ / 2 plate (1/2 wavelength plate), 2i is a plate polarizer, 2j is a 532nm wavelength mirror, 2k is a mirror, 2l is Half mirror, 2m mirror, 2n mirror, 3 photosensitive polymer film, 4a pulse laser beam reflected by mirror 2m, 4b pulse laser beam reflected by mirror 2n, and 5 induction structure . Further, θ represents the incident angle of the pulse laser beam (4a, 4b), and Λ represents the interval between the induction structure portions formed in the photosensitive polymer film 3. In the main part 1 of the pulse laser beam interference exposure apparatus having the configuration shown in FIG. 1, the laser intensity of the pulse laser beam emitted from the light source 2a is adjusted by the ND filter 2b and p-polarized light by the λ / 2 plate 2c. The ratio between the component and the s-polarized component is changed, the second harmonic (532 nm) is extracted from the KTP crystal 2d, the third harmonic (355 nm) is extracted from the BBO crystal 2e, and the 355 nm wavelength mirror 2f is used. The light having a wavelength of 355 nm is selectively reflected, the light having a wavelength of 532 nm is selectively reflected by the 532 nm wavelength mirror 2g, and the ratio of the p-polarized component and the s-polarized component is changed by the λ / 2 plate 2h. 2i transmits p-polarized light and selectively reflects s-polarized light, and selectively reflects light having a wavelength of 532 nm by the 532 nm wavelength mirror 2j. After being reflected by the mirror 2k, it is divided into two light flux pulse laser beams having the same intensity by the half mirror 21. One pulse laser beam is reflected by the mirror 2m, and the other pulse laser beam is reflected by the mirror 2n. Thereafter, as shown in FIG. 2, the pulse laser beam 4a reflected by the mirror 2m and the pulse laser beam 4b reflected by the mirror 2n are applied to the surface of the photosensitive polymer film 3 at a predetermined incident angle θ. Thus, the interference exposure is performed for a predetermined time (interference exposure time). In the initial stage of the interference exposure (or when the interference exposure time is short), the induction structure 5 as shown in FIG. 2 is formed in the photosensitive polymer film 3 at the interval Λ.

  In FIG. 2, the induction structure portion 5 formed in the photosensitive polymer film 3 has a surface relief grating (SRG) structure, specifically, a lattice-shaped structure with an interval Λ. Yes.

  Further, when the interference exposure is continued (or when the interference exposure time is extended for an interference exposure), a bell-shaped convex structure portion is formed on the surface of the photosensitive polymer film 3 as shown in FIG. The FIG. 3 is a schematic diagram showing a bell-shaped convex structure formed by subjecting a photosensitive polymer film to two-beam interference exposure using the interference exposure apparatus shown in FIG. In FIG. 3, 6 is a bell-shaped convex structure.

  Thus, in the method for forming a bell-shaped convex structure on the surface of the photosensitive polymer film of the present invention, the surface of the photosensitive polymer film is subjected to interference exposure with pulsed laser light without using a mask. Thus, the bell-shaped convex structure portion having the bell-shaped convex structure formed via the surface relief grating structure (SRG structure) is rotated in the direction of the photosensitive polymer film and the direction of interference exposure. Can be formed without rotating.

  An induction structure portion having an SRG structure is formed at an early stage in the interference exposure of the pulsed laser beam, and a bell shape which is an induction structure portion having a bell-like structure (ECL structure) by continuing the interference exposure. Since the convex structure is formed, the interference exposure of the pulsed laser beam is performed on the surface of the photosensitive polymer film by the bell-shaped convex structure having a bell-shaped convex structure via the SRG structure. It is important to do until it is formed. Thus, when forming the bell-shaped convex structure, it is important to adjust the interference exposure time of the pulse laser beam. The interference exposure time of the pulsed laser beam is not particularly limited, and can be appropriately adjusted according to the type of the photosensitive polymer, the thickness of the photosensitive polymer film, and the like.

  The shape of the bell-shaped convex structure is not particularly limited as long as it is a convex shape having a bell-shaped structure (ECL structure). Specifically, as one bell-shaped convex structure portion, for example, the height may be 80 nm (nanometers) or more (for example, 80 nm to 50 μm), preferably 0.1 μm. You may have the shape which is about (100 nm) or more (for example, 0.1-50 micrometers, More preferably, 0.1-10 micrometers, Especially 0.5-8 micrometers) grade. Moreover, as a bottom face in one bell-shaped convex structure part, the diameter is about 0.3 μm (300 nm) or more (for example, 0.3 to 100 μm, preferably 0.3 to 30 μm, more preferably 1 to 20 μm). It may have a certain shape.

  The induction structure formed via the SRG structure by interference exposure with pulsed laser light is preferably a bell-shaped structure (ECL structure). For example, a conical shape, a caldera shape, a terrace shape, a hemispherical shape It may have various convex structures such as. When the induction structure is a bell-shaped structure (ECL structure), the light collecting function can be effectively exhibited.

  In addition, the bell-shaped convex structure portion is usually continuously formed in a form having a predetermined regularity (for example, at regular intervals) on the surface of the photosensitive polymer film by interference exposure with pulsed laser light. Is formed. In the bell-shaped convex structure formed on the surface of the photosensitive polymer film, the interval between the bell-shaped convex structures (the distance between the centers of the bottom circles) is not particularly limited, but is the same as or equal to the diameter of the bottom. The above is desirable (for example, about diameter to about 10 times the diameter, preferably about diameter to about 5 times the diameter).

  The photosensitive polymer film having such a bell-shaped convex structure can be used as various optical functional materials. Specifically, a wide range of optical materials such as a macro lens array, a diffusion plate, and a photonic crystal can be used. It can be used as a functional material.

  In particular, the bell-shaped convex structure portion is preferably capable of exhibiting a light collecting function with respect to light incident from the back surface of the photosensitive polymer film. Thus, when the bell-shaped convex structure portion has a light collecting function, the photosensitive polymer film having the bell-shaped convex structure portion can be suitably used as a microlens array.

  The bell-shaped convex structure formed on the surface of the photosensitive polymer film uses, for example, an AFM (atomic force microscope) such as a device name “Nano Scope III (manufactured by Digital Instruments)”. Thus, the shape can be observed and the height can be measured.

  In addition, the diffraction efficiency of the photosensitive polymer film having the bell-shaped convex structure is determined by making a semiconductor laser (wavelength: 635 nm) incident on the photosensitive polymer film as shown in FIG. It can be determined by measuring the intensity and the intensity of transmitted light. FIG. 4 is a diagram showing an outline of the configuration of an apparatus for measuring the diffraction efficiency of a photosensitive polymer film having a bell-shaped convex structure. In FIG. 4, 7 is a laser diode (incident light source), 7a is a lens, 8 is a photosensitive polymer film (photosensitive polymer film having a bell-shaped convex structure), and 9a is a photodiode (light intensity detector). , 9b are photodiodes (light intensity detectors). In the apparatus for measuring diffraction efficiency shown in FIG. 4, the laser diode 7 is a light source and emits a semiconductor laser (wavelength: 635 nm). The semiconductor laser emitted from the laser diode 7 is focused by the lens 7a and is incident on the photosensitive polymer film 8 set in the apparatus at a predetermined incident angle (incident angle: 27 °). The light transmitted through the polymer film 8 is detected by the photodiode 9a, and the diffracted light diffracted by the photosensitive polymer film 8 is detected by the photodiode 9b.

For example, when a photosensitive polymer film formed of a polymer having a group or site containing an azobenzene skeleton in the side chain is used as the photosensitive polymer film, the second harmonic of the Nd: YAG laser. The wave (wavelength: 532 nm) is a π-π ^{* in} which a group or site containing an azobenzene skeleton in a polymer having a group or site containing an azobenzene skeleton in the side chain causes photoisomerization from a trans form to a cis form ^. Therefore, when performing interference exposure using the second harmonic (wavelength: 532 nm) of an Nd: YAG laser as a pulse laser beam, a group or site containing an azobenzene skeleton in the side chain is obtained. The group or site containing the azobenzene skeleton in the polymer possessed can cause photoisomerization from the trans isomer to the cis isomer, thereby forming an SRG structure, and By continuing the interference exposure, the SRG structure is changed (modulated), bell-shaped convex structure section of higher order the controlled bell-shaped structure (ECL structure) is formed.

  In addition, the study of forming an SRG structure in an azobenzene derivative (including a polymer) has been mainly performed using a non-pulse laser such as a cw (continuous) Ar laser as a cw (continuous) laser. Irradiation was continued until the SRG structure was formed, and the estimation of the minimum irradiation energy necessary for forming the induced structure (induced structure composed of the SRG structure) was evaluated. Therefore, after the SRG structure is formed, the irradiation is continuously performed, and the observation of how the induced structure changes has not been made so much. On the other hand, unlike cw lasers (which are non-pulse lasers), pulsed laser light has high peak power, and has a strong light-electric field gradient effect, dipole induction effect and thermal effect of polymer materials in two-beam interference exposure. The SRG structure can be formed by short-time interference exposure. For this reason, it seems that it is easy to observe what induced structural change is caused by long-time interference exposure when pulsed laser light is used.

  Further, when a pulsed laser beam having a linearly polarized characteristic is irradiated to the surface of the photosensitive polymer film with one light flux and an incident angle of 0 ° C. (perpendicular to the surface) without performing interference exposure, as shown in FIG. It was confirmed (or observed) that lattice-like inducing structures arranged in parallel to the direction of polarization were formed. This is formed by the effect of the light-electric field of the irradiation light discussed in the examination of the formation mechanism of the SRG structure and the isomerization of the photosensitive polymer accompanied by the alignment by the dipole induced in the polymer material. Lattice-like inductive structures formed in parallel and arranged in parallel are arranged at intervals slightly shorter than the wavelength of light, and the Rayleigh diffraction equation “Λ = λ / (1 ± sin θ); Λ is a grating interval, λ is an irradiation wavelength, and θ is an incident angle (an angle from a normal line).

  FIG. 5 is a schematic diagram showing the relationship between the linear polarization direction of light used in one-beam exposure and the induced structure formed by exposure, and FIG. 5A shows the case where p-polarized light is exposed. FIG. 5 (b) shows the induced structure formed when s-polarized light is exposed.

  On the other hand, when a pulsed laser beam having circular polarization characteristics is irradiated to the surface of the photosensitive polymer film with one light flux and an incident angle of 0 ° C. (perpendicular to the surface) without performing interference exposure, as shown in FIG. In the central part of the irradiation, an induced structure such as a mixture of a granular structure and a rod-like induced structure along the rotation direction of the circularly polarized light is confirmed (or observed) (FIG. 6A), and the center of the irradiation is confirmed. In the contour part (peripheral part) away from, only granular inductive structures were observed, and inductive structures arranged in parallel such as linearly polarized light were not observed (FIG. 6B).

  FIG. 6 is a schematic diagram showing the relationship between the direction of circular polarization of light used in one-beam exposure and the induced structure formed by exposure, and FIG. 6A shows the case where light having circular polarization characteristics is exposed. FIG. 6B shows the induced structure formed at the exposure contour portion (exposure peripheral portion) when light having circular polarization characteristics is exposed. FIG. 6B shows the induced structure formed at the exposure center portion (irradiation center portion). Yes.

  In this way, a regular induction structure arranged in parallel can be formed by one-beam exposure of linearly polarized light or circularly polarized light without performing two-beam interference exposure. Therefore, by combining the two-beam interference exposure and the one-beam exposure, it is possible to form a bell-shaped structure (ECL structure) controlled to a higher order or a bell-shaped convex structure portion having a structure similar to the structure. it can.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

(Example 1)
As the azobenzene derivative (azobenzene skeleton-containing monomer component), 4- (N, N-dihydroxyethylamino) -4′-nitroazobenzene (Disperse Red 19; DR19) was used, and the DR19, tolylene-2,4-diisocyanate and Was copolymerized to prepare a polymer having a group or moiety containing an azobenzene skeleton in the side chain (azobenzene skeleton side chain-containing polymer) to obtain a photosensitive polymer. This photosensitive polymer was dissolved in N, N-dimethylacetamide to prepare a solution having a concentration of 0.16% by weight. This solution was cast on a glass substrate having a clean surface at 70 ° C. to form a photosensitive polymer film having a thickness of about 800 nm (0.8 μm).

Next, two-beam interference exposure was performed on the surface of the photosensitive polymer film using the two-beam interference exposure apparatus having the configuration shown in FIG. Specifically, a p-polarized pulse (p-polarized pulse; pulse width: 10 ns, repetition: 10 Hz) of the second harmonic (wavelength: 532 nm) of an Nd: YAG laser was used as the laser light source. . Further, this p-polarized pulse is divided into two light beams having the same light intensity, and two beams having a beam diameter of 2 mm are irradiated with an irradiation light intensity of 500 μJ / pulse (power density is about 160 mW / cm ² ), Two-beam interference exposure was performed on the surface of the sample of the photosensitive polymer film at an incident angle θ of 27 °. When the exposure time for two-beam interference is set to 20 seconds (200 shots in the number of irradiation shots) and two-beam interference exposure is performed, a surface relief grating is formed on the surface of the photosensitive polymer film as an induced structure portion. A bell-shaped convex structure portion (bell-shaped convex structure portion via SRG structure) having a bell-shaped convex structure formed via the structure (SRG structure) was formed.

  The interval between the gratings predicted from the wavelength of the light source and the incident angle is about 586 nm.

(Example 2)
Using the same photosensitive polymer film as in Example 1 and a two-beam interference exposure apparatus, the two-beam interference exposure time was set to 40 seconds (number of irradiation shots: 400 shots). When two-beam interference exposure is performed, a bell-shaped convex structure portion (SRG) having a bell-shaped convex structure formed via an SRG structure on the surface of the photosensitive polymer film as an induction structure portion. A bell-shaped convex structure via structure) was formed.

(Example 3)
Using the same photosensitive polymer film as in Example 1 and a two-beam interference exposure apparatus, the two-beam interference exposure time was set to 60 seconds (number of irradiation shots: 600 shots). When two-beam interference exposure is performed, a bell-shaped convex structure portion (SRG) having a bell-shaped convex structure formed via an SRG structure on the surface of the photosensitive polymer film as an induction structure portion. A bell-shaped convex structure via structure) was formed.

Example 4
Using the same photosensitive polymer film as in Example 1 and using a two-beam interference exposure apparatus, the two-beam interference exposure time was set to 100 seconds (number of irradiation shots: 1000 shots). When two-beam interference exposure is performed, a bell-shaped convex structure portion (SRG) having a bell-shaped convex structure formed via an SRG structure on the surface of the photosensitive polymer film as an induction structure portion. A bell-shaped convex structure via structure) was formed.

(Comparative Example 1)
Using the same photosensitive polymer film as in Example 1 and a two-beam interference exposure apparatus, the two-beam interference exposure time was set to 5 seconds (number of irradiation shots: 50 shots), as in Example 1. When two-beam interference exposure was performed, an SRG structure portion was formed as an induction structure portion on the surface of the photosensitive polymer film.

(Comparative Example 2)
Using the same photosensitive polymer film as in Example 1 and a two-beam interference exposure apparatus, the two-beam interference exposure time was set to 10 seconds (the number of irradiation shots: 100 shots). When two-beam interference exposure was performed, an SRG structure portion was formed as an induction structure portion on the surface of the photosensitive polymer film.

(Evaluation)
In Examples 1 to 4 and Comparative Examples 1 and 2, the shape of the induction structure formed on the surface of the photosensitive polymer film subjected to interference exposure is changed to a device name “Nano Scope III” [manufactured by Digital Instruments Co., Ltd. ; AFM (Atomic Force Microscope)], and the height of the induced structure was evaluated. Further, the diffraction efficiency (%) of the photosensitive polymer film subjected to interference exposure was measured using a semiconductor laser (wavelength: 635 nm) as a light source, as shown in FIG. The results of these evaluations or measurements are shown in Table 1.

  7 to 12 show photographs when the interference-exposed photosensitive polymer film was observed by AFM in Examples 1 to 4 and Comparative Examples 1 and 2, respectively.

  As is clear from Table 1, the photosensitive polymer film obtained by the interference exposure method according to Examples 1 to 4 has a higher-order regular bell-shaped convex structure via the SRG structure. It was confirmed that a bell-shaped convex structure was formed.

(Example 5)
Using the same photosensitive polymer film as in Example 1 and a laser light source, the irradiation light intensity of 500 μJ irradiation (exposure light intensity per unit area is 15.5) under the exposure condition of one beam normal incidence (θ = 0). When a linearly polarized p-polarized light having 9 mJ / cm ² ) is irradiated at an exposure time of 20 seconds (the number of irradiation shots is 200 shots), an induced structure portion is formed on the surface of the photosensitive polymer film as shown in FIG. A surface relief grating structure (SRG structure) as shown was formed.

(Example 6)
Using the same photosensitive polymer film as in Example 1 and a laser light source, the irradiation light intensity of 500 μJ irradiation (exposure light intensity per unit area is 15.5) under the exposure condition of one beam normal incidence (θ = 0). When the linearly polarized p-polarized light having 9 mJ / cm ² ) was irradiated at an exposure time of 30 seconds (the number of irradiation shots was 300 shots), an induced structure portion was formed on the surface of the photosensitive polymer film as shown in FIG. A surface relief grating structure (SRG structure) as shown was formed.

(Example 7)
Using the same photosensitive polymer film as in Example 1 and a laser light source, the irradiation light intensity of 500 μJ irradiation (exposure light intensity per unit area is 15.5) under the exposure condition of one beam normal incidence (θ = 0). When linearly polarized p-polarized light having 9 mJ / cm ² ) is irradiated at an exposure time of 50 seconds (the number of irradiation shots is 500 shots), an induced structure is formed on the surface of the photosensitive polymer film as shown in FIG. A surface relief grating structure (SRG structure) as shown was formed.

(Example 8)
Using the same photosensitive polymer film as in Example 1 and a laser light source, the irradiation light intensity of 500 μJ irradiation (exposure light intensity per unit area is 15.5) under the exposure condition of one beam normal incidence (θ = 0). When circularly polarized light having 9 mJ / cm ² ) is irradiated at an exposure time of 30 seconds (the number of irradiation shots is 300 shots), the surface as shown in FIG. A relief grating structure (SRG structure) was formed. The SRG structure includes a partial spiral structure.

Example 9
Using the same photosensitive polymer film as in Example 1 and a laser light source, the irradiation light intensity of 500 μJ irradiation (exposure light intensity per unit area is 15.5) under the exposure condition of one beam normal incidence (θ = 0). When circularly polarized light having 9 mJ / cm ² ) is irradiated at an exposure time of 50 seconds (the number of irradiation shots is 500 shots), the surface as shown in FIG. A relief grating structure (SRG structure) was formed. The SRG structure includes a partial spiral structure.

  In addition, FIGS. 13-17 is a figure which shows the photograph at the time of observing the photosensitive polymer film by which one light beam exposure was carried out by AFM in Examples 5-9, respectively. Specifically, FIGS. 13 to 17 respectively show photosensitive polymer films exposed to one light beam in each of Examples 5 to 9 (that is, linearly polarized light under the exposure condition of one light beam normal incidence (θ = 0). The shape of the induced structure formed on the surface of the photosensitive polymer film exposed to the p-polarized light or the circularly polarized light with a predetermined exposure time) is designated as “Nano Scope III” [Digital Instrument It is a figure which shows the photograph at the time of observing using a company make; AFM (atomic force microscope). As shown in FIGS. 13 to 17, the formation of the SRG structure by single-beam exposure of p-polarized light or circularly-polarized light is an elementary process in forming a higher-order bell-shaped convex structure by two-beam interference exposure. It was confirmed that it would be one.

FIG. 1 is a diagram showing an outline of the configuration of an apparatus used when irradiating pulsed laser light by two-beam interference exposure. FIG. 2 is a schematic view showing a situation in which a pulsed laser beam is exposed to a two-beam interference on a photosensitive polymer film using the interference exposure apparatus shown in FIG. 1, and an induced structure to be formed. FIG. 3 is a schematic diagram showing a bell-shaped convex structure formed by subjecting a photosensitive polymer film to two-beam interference exposure using the interference exposure apparatus shown in FIG. FIG. 4 is a diagram showing an outline of the configuration of an apparatus for measuring the diffraction efficiency of a photosensitive polymer film having a bell-shaped convex structure. FIG. 5 is a schematic diagram showing the relationship between the linear polarization direction of light used in one-beam exposure and the induced structure formed by exposure, and FIG. 5A shows the case where p-polarized light is exposed. FIG. 5 (b) shows the induced structure formed when s-polarized light is exposed. FIG. 6 is a schematic diagram showing the relationship between the direction of circular polarization of light used in one-beam exposure and the induced structure formed by exposure, and FIG. 6A shows the case where light having circular polarization characteristics is exposed. FIG. 6B shows the induced structure formed at the exposure contour portion (exposure peripheral portion) when light having circular polarization characteristics is exposed. FIG. 6B shows the induced structure formed at the exposure center portion (irradiation center portion). Yes. FIG. 7 is a view showing a photograph when the photosensitive polymer film subjected to interference exposure in Example 1 is observed by AFM. FIG. 8 is a view showing a photograph when the photosensitive polymer film subjected to interference exposure in Example 2 is observed by AFM. FIG. 9 is a view showing a photograph when the interference-exposed photosensitive polymer film in Example 3 is observed by AFM. FIG. 10 is a view showing a photograph when the interference-exposed photosensitive polymer film in Example 4 is observed by AFM. FIG. 11 is a view showing a photograph when the photosensitive polymer film subjected to interference exposure in Comparative Example 1 is observed by AFM. FIG. 12 is a view showing a photograph when the photosensitive polymer film subjected to interference exposure in Comparative Example 1 is observed by AFM. FIG. 13 is a view showing a photograph when the photosensitive polymer film exposed to one light beam in Example 5 is observed by AFM. FIG. 14 is a view showing a photograph when the photosensitive polymer film exposed to one light beam in Example 6 is observed by AFM. FIG. 15 is a view showing a photograph when the photosensitive polymer film exposed to one light beam in Example 7 is observed by AFM. FIG. 16 is a view showing a photograph when the photosensitive polymer film exposed to one light beam in Example 8 is observed by AFM. FIG. 17 is a view showing a photograph when the photosensitive polymer film exposed to one light beam in Example 9 is observed by AFM.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main part 2a of pulse laser beam interference exposure apparatus is light source 2b ND (neutral density) filter 2c λ / 2 plate (1/2 wavelength plate)
2d KTP crystal 2e BBO crystal 2f 355nm wavelength mirror 2g 532nm wavelength mirror 2h λ / 2 plate (1/2 wavelength plate)
2i Plate Polarizer 2j 532 nm Wavelength Mirror 2k Mirror 2l Half Mirror 2m Mirror 2n Mirror 3 Photosensitive Polymer Film 4a Pulse Laser Light Reflected by Mirror 2m 4b Pulse Laser Light Reflected by Mirror 2n 5 Inductive Structure Portion θ Pulse Laser Incident angle of light (4a, 4b) [Lambda] interval between induction structures formed on the photosensitive polymer film 3 6 bell-shaped convex structure 7 laser diode 7a lens 8 photosensitive polymer film (bell-shaped convex structure) Photosensitive polymer film)
9a photodiode 9b photodiode

Claims (11)

A method of forming a bell-shaped convex structure on the surface of a polymer film having a photosensitive function, the wavelength causing the polymer film to exhibit a photosensitive function on the surface of the polymer film having a photosensitive function A bell-shaped convex structure portion having a bell-shaped convex structure formed via a surface relief grating structure is obtained by interfering exposure of a pulse laser beam in a region without using a mask. A method for forming a bell-shaped convex structure on a surface of a photosensitive polymer film, wherein the film is formed without rotating the position of the film or the direction of interference exposure. The photosensitive polymer film according to claim 1, wherein the polymer film having a photosensitive function is a polymer film capable of exhibiting a photosensitive function by photoisomerization, photorefractive property, photocrosslinking property or photodegradability. A method for forming a bell-shaped convex structure on a surface. The bell-shaped on the surface of the photosensitive polymer film according to claim 1 or 2, wherein the polymer film having a photosensitive function is formed of a polymer having a group or a part containing an azobenzene skeleton in a side chain. Method for forming convex structure. A polymer having a group or moiety containing an azobenzene skeleton in the side chain is a polymer of an azobenzene dye having at least two hydroxyl groups and a monomer component having at least two reactive functional groups for hydroxyl groups. The method for forming a bell-shaped convex structure on the surface of the photosensitive polymer film according to claim 3. The method for forming a bell-shaped convex structure portion on the surface of the photosensitive polymer film according to any one of claims 1 to 4, wherein the thickness of the polymer film is 100 nanometers or more. The method for forming a bell-shaped convex structure on the surface of the photosensitive polymer film according to any one of claims 1 to 5, wherein the height of the bell-shaped convex structure is 80 nanometers or more. The method for forming a bell-shaped convex structure on the surface of the photosensitive polymer film according to any one of claims 1 to 6, wherein the pulse laser beam is a pulse laser beam having a pulse width of 500 µsec or less. The method for forming a bell-shaped convex structure portion on the surface of the photosensitive polymer film according to any one of claims 1 to 7, wherein the pulsed laser light has a light intensity of 10 mW / cm ^{2 to 1} W / cm ^2. . The method for forming a bell-shaped convex structure portion on the surface of the photosensitive polymer film according to any one of claims 1 to 8, wherein the pulsed laser light has p-polarization polarization characteristics. The method for forming a bell-shaped convex structure portion on the surface of the photosensitive polymer film according to any one of claims 1 to 8, wherein the pulsed laser beam has a polarization property of a circular polarization property. The bell-shaped convex structure formed on the surface of the polymer film having a photosensitive function can exhibit a light collecting function with respect to light incident from the back surface of the polymer film. The method for forming a bell-shaped convex structure on the surface of the photosensitive polymer film according to any one of the items.

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