JPWO2009001906A1 - Alignment film manufacturing method, liquid crystal optical element, and optical head device - Google Patents

Abstract

The present invention provides a method of forming an alignment film having a high alignment regulating force. Also provided are a liquid crystal optical element and an optical head device having excellent optical characteristics and reliability. In the method of the present invention, after an alignment film composition containing fine particles and a matrix component having a higher etching rate by ion beam than the fine particles is applied on a substrate, the alignment film composition is subjected to heat treatment to form a matrix. Advance the polymerization of the components. Next, the film made of the alignment film composition after the heat treatment is obliquely irradiated with an ion beam to form a groove parallel to the ion incident direction. The alignment film composition preferably contains fine particles as a main component. A plasma beam may be irradiated instead of the ion beam.

Description

  The present invention relates to an alignment film manufacturing method, a liquid crystal optical element, and an optical head device.

Concavities and convexities called pits are provided on the surface of an optical disc such as a CD (compact disk) and a DVD (digital versatile disk).
In the optical head device, the information recorded in the pits can be read by irradiating the optical disk with laser light and detecting the reflected light.

  2. Description of the Related Art Conventionally, an optical head device that guides reflected light from an optical disk to a detection unit using a beam splitter is known. According to this method, light emitted from the semiconductor laser passes through a beam splitter, a collimator, an aberration correction element, a wave plate, an objective lens, and the like, and then is collected on an optical disk. The light reflected by the optical disk passes through the objective lens and the liquid crystal lens element again, is reflected by the beam splitter, and then enters the detector. Here, the liquid crystal lens element is used as a means for correcting spherical aberration caused by the thickness of the cover layer provided on the optical disc, in addition to changing the polarization state of incident light.

  By the way, liquid crystal optical elements such as liquid crystal lens elements are classified into several modes depending on the initial alignment state of the liquid crystal layer, the operation state and the alignment state when a voltage is applied, and the like.

  For example, a TN (Twisted Nematic; hereinafter referred to as TN) mode uses liquid crystal molecules having positive dielectric anisotropy and aligns them substantially horizontally with respect to the substrate, and between the upper and lower substrates. It is designed to be in a twisted state. The vertical alignment (hereinafter referred to as VA) mode uses liquid crystal molecules having a negative dielectric anisotropy and is aligned substantially perpendicular to the substrate.

  In such a liquid crystal optical element, an alignment film is formed on each substrate sandwiching the liquid crystal layer in order to make the operation direction of the liquid crystal uniform when a voltage is applied.

  For the alignment film, an organic material such as polyimide is dissolved in an appropriate solvent, and this is applied onto a substrate by spin coating or the like to form a film made of the alignment film material, and then subjected to an alignment process. Formed by.

  As a method of alignment treatment, a rubbing method has been conventionally known (for example, see Patent Document 1). In the rubbing method, liquid crystal molecules are aligned in that direction by rubbing the surface of the alignment film in one direction with a rubbing cloth such as nylon or rayon. For example, a rubbing cloth is wound and fixed on the surface of a metal-made cylindrical rubbing roller, and the rubbing roller is rotated at an appropriate speed while moving the rubbing roller on the film made of the alignment film material. Make the rubbing cloth rub on the surface. Such rubbing mechanism is considered to be caused by liquid crystal molecules fitting into grooves on the alignment film surface formed by rubbing. In addition, it is considered that an electrostatic force that aligns liquid crystal molecules in one direction is applied to the alignment film by rubbing.

  However, in the alignment treatment by the rubbing method, the rubbing cloth rubs the surface of the film made of the alignment film material, which causes the following problems. That is, (1) Dust is likely to be generated from the rubbing cloth, (2) The element is destroyed due to static electricity during rubbing, or the alignment regulating force of the alignment film is reduced, (3) Damage to the rubbing cloth For example, alignment defects are partially caused and alignment unevenness is likely to occur. (4) It is difficult to impart uniform alignment characteristics over the entire film made of the alignment film material. Furthermore, there is also a problem that it is difficult to perform an alignment treatment on the surface of a film made of an alignment film material having a fine step (unevenness) that cannot reach the tip of the rubbing cloth.

  In addition, since organic materials are easily decomposed by light, heat, etc., when used as alignment film materials, there are the following problems.

  In general, an organic material absorbs light having a short wavelength (for example, a wavelength of 450 nm or less) and causes a decomposition reaction or the like. For this reason, the alignment film made of an organic material is likely to be deteriorated by short-wavelength light emitted from the light source of the optical head device. When the alignment film is deteriorated, alignment failure of liquid crystal molecules occurs, so that the optical characteristics of the liquid crystal optical element are deteriorated. In particular, in recent years, in order to increase the recording density, development of an optical head device using a semiconductor laser capable of outputting blue wavelength light (wavelength 390 nm to 430 nm) as a light source has been advanced. When such a light source is used, the reliability decreases due to the deterioration of the alignment film.

  Therefore, a method for aligning liquid crystal molecules with an alignment film by an oblique deposition method or an oblique sputtering method of an inorganic material has been proposed instead of the alignment film rubbed with an organic material. For example, Patent Document 2 describes a method of forming an alignment film made of an inorganic material by causing sputtered particles to enter the substrate obliquely. However, in the case of the oblique sputtering method, sputtered particles are wasted and it is difficult to accurately control the incident angle. Further, in the oblique deposition method, in order to ensure the accuracy of the oblique incident angle, the distance between the evaporation source and the substrate has to be increased, and there is a problem that the apparatus is easily increased in size. In addition, the number of substrates that can be mounted is limited, and since batch processing is usually performed, there is a problem that the tact time is long and the productivity is low.

  On the other hand, conventionally, an alignment processing method using an ion beam is also known. For example, when an ion beam containing argon ions is irradiated onto a DLC (diamond-like carbon) film, an alignment regulating force equivalent to that obtained when the polyimide film is rubbed is obtained. Further, according to this method, the pretilt angle can be controlled well.

  However, since the DLC film has a large absorption in the short wavelength range of visible light (wavelength of 500 nm or less), an optical head device using laser light as a light source, particularly an optical head using light of blue or shorter wavelength as a light source. Not suitable for equipment. On the other hand, when a silicon oxide film is used instead of the DLC film, the above problem is solved, but there is a problem that the alignment regulating force on the liquid crystal molecules is lowered and the alignment order of the liquid crystal tends to be insufficient.

  It has also been proposed to use an inorganic porous film instead of a high-density silicon oxide film. For example, Patent Document 3 describes that a vertical alignment film is obtained by forming a porous silicon oxide film by applying a precursor solution of a porous silica material and then performing a heat treatment. However, there is a problem that the operation direction of liquid crystal molecules cannot be made constant when a voltage is applied only by forming a porous film. That is, since the vacancies are formed substantially perpendicular to the surface of the porous film, there is a problem that when the liquid crystal molecules are turned in the horizontal direction by applying a voltage, the directions of the liquid crystal molecules are not aligned. there were.

JP 2001-318382 A JP 2004-170744 A JP 2004-69870 A

  The present invention has been made in view of the above problems. That is, an object of the present invention is to provide a method for producing an alignment film having a high alignment regulating force.

  Another object of the present invention is to provide a liquid crystal optical element and an optical head device having excellent optical characteristics and reliability.

  Other objects and advantages of the present invention will become apparent from the following description.

According to a first aspect of the present invention, there is provided a step of applying an alignment film composition containing fine particles and matrix components having different fine particles and an ion beam or plasma beam etching rate on a substrate;
A step of performing a heat treatment on the alignment film composition to advance polymerization of the matrix component;
A step of forming grooves parallel or perpendicular to the incident direction of the beam on the surface of the film made of the alignment film composition by obliquely making the beam incident on the film made of the alignment film composition after the heat treatment It is related with the manufacturing method of the oriented film characterized by having.

  In the first aspect of the present invention, the alignment film composition preferably contains the fine particles as a main component.

  In the first aspect of the present invention, when the matrix component has an etching rate larger than that of the fine particles, the pitch of the grooves is preferably substantially equal to the average particle diameter of the fine particles.

In the first aspect of the present invention, the matrix component includes Ca, Li, Al, Mg, Ce, Si, Sn, Y, Hf, Zr, Zn, Ta, Ti, CaF ₂ , LiF, AlF ₃ , MgF _2. , CeF ₃ , Al ₂ O ₃ , SiO ₂ , SnO ₂ , MgO, Y ₂ O ₃ , HfO ₂ , ZrO ₂ , ZnO, Ta ₂ O ₅ , CeO ₂ , Nb ₂ O ₅ , TiO, TiO ₂ or ITO It is preferable to contain as a structural component.

The second aspect of the present invention is a step of applying an alignment film composition comprising fine particles and a solvent on a substrate;
Performing a heat treatment on the alignment film composition to remove the solvent;
By making an ion beam or a plasma beam obliquely enter the film made of the alignment film composition after the heat treatment, grooves parallel or perpendicular to the incident direction of the beam are formed on the surface of the film made of the alignment film composition. And a process for forming the alignment film.

  2nd aspect of this invention WHEREIN: It is preferable that the pitch of the said groove | channel is substantially equal to the average particle diameter of the said microparticle.

  In the second aspect of the present invention, the fine particles preferably have an average particle size of 70 nm or less.

In the first aspect and the second aspect of the present invention, the fine particles include Ca, Li, Al, Mg, Ce, Si, Sn, Y, Hf, Zr, Zn, Ta, Ti, CaF ₂ , LiF, and AlF. _{3, MgF 2, CeF 3,} Al 2 O 3, SiO 2, SnO 2, MgO, Y 2 O 3, HfO 2, ZrO 2, ZnO, Ta 2 O 5, CeO 2, Nb 2 O 5, TiO, TiO Preferably it consists of ₂ or ITO.

A third aspect of the present invention is a step of applying an alignment film composition comprising fine particles composed of SiO ₂ and a matrix component composed of tetraethoxysilane on a substrate;
A step of performing a heat treatment on the alignment film composition to advance polymerization of the matrix component;
By making an ion beam or a plasma beam obliquely enter the film made of the alignment film composition after the heat treatment, grooves parallel or perpendicular to the incident direction of the beam are formed on the surface of the film made of the alignment film composition. And forming a process,
In the alignment film composition, the fine particles are present in a ratio of 40% by mass or more with respect to the total amount of the fine particles and the matrix component in terms of SiO _2. .

  In the third aspect of the present invention, it is preferable that the matrix component has a higher etching rate than the fine particles, and the pitch of the grooves is substantially equal to the average particle diameter of the fine particles.

  In the third aspect of the present invention, the fine particles preferably have an average particle size of 70 nm or less.

  A 4th aspect of this invention is related with the liquid crystal optical element provided with the orientation film manufactured by the 1st aspect, the 2nd aspect, or the 3rd aspect of this invention.

  A fifth aspect of the present invention relates to an optical head device having the liquid crystal optical element of the fourth aspect of the present invention.

  According to the first aspect of the present invention, an alignment film composition containing fine particles and a matrix component is used, and an ion beam or a plasma beam is incident obliquely on the surface of the film made of the alignment film composition. A groove parallel or perpendicular to the incident direction of the beam is formed. Thereby, an alignment film having a high alignment regulating force can be manufactured.

  According to the second aspect of the present invention, an ion beam or a plasma beam is obliquely incident using an alignment film composition composed of fine particles and a solvent, whereby the beam is incident on the surface of the film composed of the alignment film composition. A groove parallel or perpendicular to the incident direction is formed. Thereby, an alignment film having a high alignment regulating force can be manufactured.

According to the third aspect of the present invention, an ion beam or a plasma beam is obliquely incident using an alignment film composition containing fine particles made of SiO ₂ and a matrix component made of tetraethoxysilane. In the alignment film composition, the fine particles are present in a proportion of 40% by mass or more based on the total amount of the fine particles and the matrix component in terms of SiO ₂ . Thereby, an alignment film having a high alignment regulating force can be manufactured.

  According to the 4th aspect of this invention, it can be set as the liquid crystal optical element excellent in the optical characteristic and reliability.

  According to the fifth aspect of the present invention, an optical head device having excellent optical characteristics and reliability can be obtained.

It is a flowchart which shows the formation method of the alignment film in this Embodiment. It is a figure explaining the formation method of the alignment film in this Embodiment. It is a figure explaining the formation method of the alignment film in this Embodiment. (A) is a perspective view of the alignment film composition surface after finishing heat processing, (b) is sectional drawing which follows the II line | wire of (a). (A) is a perspective view which shows a mode that the groove | channel was formed in parallel with the incident direction of ion after ion beam irradiation, (b) is sectional drawing which follows the II-II line of (a). (A) is a perspective view which shows a mode that the groove | channel was formed perpendicularly | vertically with the incident direction of ion after ion beam irradiation, (b) is sectional drawing which follows the III-III line of (a). It is the schematic of the ion beam irradiation apparatus used by this Embodiment. It is a cross-sectional schematic diagram of the liquid crystal lens element which can apply this invention. It is a block diagram of the optical head apparatus which can apply this invention. It is another block diagram of the optical head apparatus which can apply this invention. It is a cross-sectional schematic diagram of the liquid crystal element of FIG. (A) is the SEM photograph of the thin film formed using the alignment film composition before ion beam irradiation, (b) is the SEM photograph of the alignment film obtained by ion beam irradiation. It is a comparison figure of the twist angle of an Example and a comparative example. It is a figure which shows the change rate of the twist angle with respect to integrated light quantity about an Example and a comparative example. (A) is the SEM photograph of the thin film formed using the alignment film composition before ion beam irradiation, (b) is the SEM photograph of the alignment film obtained by ion beam irradiation. It is a figure which shows the change rate of the twist angle with respect to a high temperature, high humidity environment test about an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Electrode layer 3 Alignment film composition 4 Alignment film 5 Groove 11 Chamber 12 Substrate holder 13 Substrate 14 Ion gun 15 Gas inlet 16 Electrode system 17 Exhaust outlet 18 Electron gun for neutralization 21 Liquid crystal lens element 22, 42 First Transparent substrate 23, 43 Second transparent substrate 24 First electrode layer 25, 45 First alignment film 26 Second electrode layer 27 Second alignment film 28 Sealing material 29 Liquid crystal layer 30 Liquid crystal cell 31 Power source 32, 41 Optical head device 33 Light source 34 Diffraction grating 35 Phase difference element 36 Objective lens 37, 38 Optical disk 39, 40, 52 Optical detector 42 Semiconductor laser 43 Collimator lens 44 Liquid crystal element 45 Voltage controller 46 Polarizer 47 λ / 4 plate 48 Actuator 49, 51 Condensing lens 50 Optical recording medium 61, 62 Transparent substrate 63 Liquid crystal layer 64, 65 Transparent Pole 66, 67 alignment film 68 liquid crystal molecules 69 sealing material

  In order to align the operation direction of the liquid crystal molecules when a voltage is applied, the initial alignment state of the liquid crystal is preferably inclined with respect to the substrate. In other words, in a state where no voltage is applied, the major axis of the liquid crystal molecules may be inclined with a pretilt angle with respect to the direction perpendicular to the substrate. Based on this idea, a method has been disclosed so far in which the pores are inclined obliquely by irradiating the porous film with an ion beam (see, for example, JP-A-2005-31196). On the other hand, the inventor performs heat treatment on the alignment film composition containing fine particles, and then injects an ion beam or a plasma beam obliquely to form a groove on the surface of the film made of the alignment film composition. The present inventors have found a method for forming an alignment film having a high alignment regulating force by forming a film. Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a flowchart showing a method for forming an alignment film in the present embodiment. 2 and 3 are cross-sectional views of the substrate for explaining the method of forming the alignment film. In FIGS. 2 and 3, the same reference numerals indicate the same parts.

  First, a substrate 1 on which an electrode layer 2 is formed is prepared (step 1).

  As the substrate 1, a transparent substrate made of a material having a high transmittance for visible light can be used. Specifically, in addition to inorganic glass such as alkali glass, alkali-free glass and quartz glass, polyester, polycarbonate, polyether, polysulfone, polyethersulfone, polyvinyl alcohol, and fluorine-containing polymers such as polyvinyl fluoride, etc. A substrate made of a transparent material is exemplified.

A transparent conductive material can be used for the electrode layer 2. For example, ITO (Indium Tin Oxide), SnO ₂ or ZnO can be used as the electrode material. However, in the present embodiment, the electrode layer 2 may not be provided.

  Next, as shown in FIG. 2, an alignment film composition 3 is applied on the substrate 1 provided with the electrode layer 2 (step 2).

  In the present invention, an insulating layer, a light shielding layer, or the like can be provided between the substrate 1 and the electrode layer 2 as used in a normal liquid crystal optical element. In addition, an insulating layer, a light shielding layer, or the like can be provided between the electrode layer 2 and the alignment film composition 3. Furthermore, a non-reflective layer or the like can be provided on the surface of the substrate 1 opposite to the side on which the electrode layer 2 is provided.

  The coating method of the alignment film composition 3 is not particularly limited, and various methods can be used. Examples thereof include a spin coater, an air knife coater, a blade coater, a bar coater, a gravure coater, a roll coater, a die coater, a knife coater, and a screen coater.

The alignment film composition 3 includes fine particles and a matrix component. These mixing ratios can be appropriately changed. For example, if the alignment film composition comprising a matrix component composed of fine particles and tetraethoxysilane consisting SiO _2, fine particles in the alignment film composition, the total amount of SiO ₂ reduced mass of the mass and the matrix component of the fine particles On the other hand, by being present at a ratio of 40% by mass or more, an alignment film having a high alignment regulating force can be obtained. Incidentally, SiO ₂ mass in terms of the matrix components is obtained from tetraethoxysilane precursors.

From the viewpoint of increasing the light resistance of the alignment film, the alignment film composition preferably contains fine particles as a main component. In the present invention, the “main component” refers to a component having the maximum solid content ratio among the components constituting the alignment film composition. For example, when SiO ₂ is used as the fine particles and tetraethoxysilane is used as the matrix component, the fine particles in the alignment film composition are 60% by mass or more based on the total amount of the fine particles and the matrix component in terms of SiO _2. Preferably, it exists in the ratio of 80 mass% or more.

  In the present embodiment, for example, fine particles having an average particle diameter of 5 nm or more can be used. However, from the viewpoint of increasing the orientation regulating force, it is preferable that the average particle diameter of the fine particles is small. Specifically, the average particle size is preferably 100 nm or less, and more preferably 70 nm or less. In the present invention, “average particle size of fine particles” refers to the average primary particle size of fine particles. The shape of the fine particles is not particularly limited, and may be a spherical shape, a flat plate shape, or a chain shape in which spherical shapes are connected. In the case of a spherical shape, it may be hollow.

As fine particles, Ca (calcium), Li (lithium), Al (aluminum), Mg (magnesium), Ce (cerium), Si (silicon), Sn (tin), Y (yttrium), Hf (hafnium), Zr Metals such as (zirconium), Zn (zinc), Ta (tantalum) and Ti (titanium). The fine particles may be oxides, fluorides, nitrides or oxynitrides of these metals, or composite compounds thereof.
Specifically, CaF ₂ (calcium fluoride), LiF (lithium fluoride), AlF ₃ (aluminum fluoride), MgF ₂ (magnesium fluoride), CeF ₃ (cerium fluoride), Al ₂ O ₃ (oxidation) Aluminum), SiO ₂ (silicon dioxide), SnO ₂ (tin oxide), MgO (magnesium oxide), Y ₂ O ₃ (yttrium oxide), HfO ₂ (hafnium oxide), ZrO ₂ (zirconium oxide), ZnO (zinc oxide) ), Ta ₂ O ₅ (tantalum pentoxide), CeO ₂ (cerium oxide), Nb ₂ O ₅ (niobium pentoxide), TiO (titanium monoxide), TiO ₂ (titanium dioxide), ITO (Indium Tin Oxide), etc. Is mentioned. Furthermore, the fine particles may be at least one selected from the group consisting of the above metals and oxides thereof, fluorides, nitrides, oxynitrides, and composite compounds thereof. Furthermore, the fine particles may have a structure in which silanol groups on the fine particle surfaces are substituted with organic groups. Organic groups include alkyl groups, aryl groups, and alkenyl groups, and alkyl groups in which some hydrogen atoms are substituted with halogen atoms, aromatic groups, alicyclic groups, epoxy groups, vinyl groups, mercapto groups, or amino groups. It can be selected from the group consisting of: In this case, only one type of organic group may be used, or two or more types may be combined.

As the matrix component, materials having different etching rates by fine particles and ion beams are used. Even a material having the same composition as the fine particles can be used as a matrix component because the etching rate is different if the density is different from that of the fine particles. The components constituting the matrix component are Ca (calcium), Li (lithium), Al (aluminum), Mg (magnesium), Ce (cerium), Si (silicon), Sn (tin), Y as well as the fine particles. Metals such as (yttrium), Hf (hafnium), Zr (zirconium), Zn (zinc), Ta (tantalum), Nb (niobium), and Ti (titanium) can be used. In addition, oxides, fluorides, nitrides, oxynitride compounds, or composites of these metals can also be used. For example, CaF ₂ (calcium fluoride), LiF (lithium fluoride), AlF ₃ (aluminum fluoride), MgF ₂ (magnesium fluoride), CeF ₃ (cerium fluoride), Al ₂ O ₃ (aluminum oxide), SiO ₂ (silicon dioxide), SnO ₂ (tin oxide), MgO (magnesium oxide), Y ₂ O ₃ (yttrium oxide), HfO ₂ (hafnium oxide), ZrO ₂ (zirconium oxide), ZnO (zinc oxide), Ta ₂ O ₅ (tantalum pentoxide), CeO ₂ (cerium oxide), Nb ₂ O ₅ (niobium pentoxide), TiO (titanium monoxide), TiO ₂ (titanium dioxide), ITO (Indium Tin Oxide), or the like. . Furthermore, at least one selected from the group consisting of the above metals and oxides thereof, fluorides, nitrides, oxynitrides, and composite compounds thereof can be used as the matrix constituent component.

The matrix component is preferably an inorganic material having an organic group. As an example, organosiloxanes represented by the general formula SiR ¹ R ² R ³ R ⁴ can be given. Here, ^{one to four} of R ¹ , R ² , R ³ and R ⁴ are each independently selected from the group consisting of (a) a hydroxyl group, an alkoxyl group, an aryloxy group and an acyloxy group. be able to. The remainder is (b) a hydrogen atom, an alkyl group, an aryl group and an alkenyl group, and some hydrogen atoms are halogen atoms, aromatic groups, alicyclic groups, epoxy groups, vinyl groups, mercapto groups or amino groups. It can be selected from the group consisting of alkyl groups substituted with In this case, only one type of organosiloxane may be used, or two or more types may be combined. Other examples of inorganic materials having an organic group that can be used as a matrix component include pentaethoxy tantalum (Ta (OC ₂ H ₅ ) ₅ ) and tetraethoxy titanium (Ti (OC ₂ H ₅ ) ₄ ). It is done.

  The matrix component is not limited to an inorganic material as long as it has a different etching rate from the fine particles, and an organic material such as polyimide can also be used. However, it is preferable to use an inorganic material as a matrix component from the viewpoint of improving the light resistance of the alignment film. In particular, inorganic materials are preferably used in applications where a blue laser (wavelength 390 nm to 430 nm) is used as a light source.

  The alignment film composition 3 can contain a solvent in order to improve the film formability. As the solvent, alcohol, ketone, amide, ester, or the like can be used. These solvents can be used alone or in combination of two or more.

  Examples of the alcohol solvent include methanol, ethanol, n-propanol, isopropanol n-butanol, isobutanol s-butanol, t-butanol, pentanol, hexanol, octanol, cyclohexanol, benzyl alcohol, ethylene glycol, propylene glycol, Butylene glycol, diethylene glycol, dipropylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, propylene Glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monopropyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether and dipropylene glycol And monopropyl ether. These can be used alone or in combination of two or more.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl isobutyl ketone, and cyclohexanone. These can be used alone or in combination of two or more.

  Examples of amide solvents include formamide, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N- Ethylacetamide, N, N-diethylacetamide, N-methylpropionamide, N-methylpyrrolidone, N-formylmorpholine, N-formylpiperidine, N-formylpyrrolidine, N-acetylmorpholine, N-acetylpiperidine and N-acetylpyrrolidine And so on. These can be used alone or in combination of two or more.

  Examples of ester solvents include diethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl acetate. Ether, Diethylene glycol monomethyl ether, Diethylene glycol monoethyl ether, Diethylene glycol mono-n-butyl ether, Propylene glycol monomethyl ether, Propylene glycol monoethyl ether, Propylene glycol monopropyl ether, Propylene glycol monobutyl ether, Diacetate Propylene glycol monomethyl ether, dipropylene glycol monoethyl ether acetate, propylene Such as phosphate methyl and ethyl propionate and the like. These can be used alone or in combination of two or more.

  The alignment film composition 3 can also contain a surfactant. As the surfactant, any of a nonionic surfactant, an anionic surfactant, a cationic surfactant and an amphoteric surfactant can be used.

  After the alignment film composition 3 is applied on the substrate 1, the alignment film composition 3 is subjected to heat treatment (step 3).

  When the alignment film composition 3 contains a solvent, Step 3 can be a process of performing a second heat treatment (post-baking) after performing the first heat treatment (pre-baking). That is, after the solvent is mainly removed by the first heat treatment, the polymerization of the matrix component can be advanced by the second heat treatment. In general, the temperature of the first heat treatment can be 70 ° C. to 200 ° C., and the temperature of the second heat treatment can be 200 ° C. to 450 ° C.

  In addition, in order to assist superposition | polymerization of a matrix component, a catalyst can be included in the alignment film composition 3. FIG. As the catalyst, either acid or alkali may be used.

  Acid catalysts include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, phosphoric acid and boric acid, as well as formic acid, acetic acid, propionic acid, oxalic acid, p-toluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, Mention may be made of organic acids such as trifluoroacid and trichloroacetic acid. These acid catalysts can be used alone or in combination of two or more.

  Examples of the alkali catalyst include inorganic bases such as ammonia, sodium hydroxide, potassium hydroxide, barium hydroxide and calcium hydroxide. Also, alkanolamines such as methanolamine, ethanolamine, propanolamine, butanolamine, dimethanolamine, diethanolamine and dipropanolamine, methoxymethylamine, methoxyethylamine, methoxypropylamine, methoxybutylamine, ethoxymethylamine, ethoxyethylamine, Alkoxyalkylamines such as ethoxypropylamine and ethoxybutylamine, and alkyls such as methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, trimethylamine, triethylamine, tripropylamine and tributylamine Mention may also be made of organic bases such as amines. These alkali catalysts can be used alone or in combination of two or more.

  Next, the film made of the alignment film composition 3 after the heat treatment is irradiated with an ion beam (step 4). Thereby, the alignment film 4 is obtained.

In step 4, the ion beam is incident on the substrate 1 in an inclined state. That is, the ion beam is irradiated obliquely to the film made of the alignment film composition 3 after the heat treatment. The incident angle is generally in the range of 40 degrees to 85 degrees with respect to the normal of the substrate.
However, since an incident angle suitable for forming a desired groove to be described later varies depending on the type of material constituting the alignment film composition, it is preferable to set it appropriately according to the type of material.

  The film made of the alignment film composition 3 after the heat treatment is configured in a state where fine particles are dispersed in the matrix component, specifically, in a state where materials having different etching rates of the fine particles and the matrix component are arranged at appropriate intervals. It is preferable. With such a structure, a high etching rate, for example, a matrix component is selectively etched by ion beam irradiation. As a result, periodic irregularities can be formed on the surface of the resulting alignment film. Here, the concave portion corresponds to a portion between the fine particles, and the convex portion corresponds to the fine particle portion. Further, by irradiation with an ion beam, the fine particles arranged in parallel (or perpendicular) to the incident direction of ions are connected to each other by the influence of the oblique effect or the like, and the granular fine particles grow in an elliptical shape. Thus, the recess forms a groove parallel (or perpendicular) to the ion incident direction. Thus, in the present invention, it is necessary to form grooves in parallel (or perpendicular) to the incident direction of ions. The reason will be described with reference to FIGS.

  FIG. 4A is a perspective view schematically showing the surface of a film made of the alignment film composition after heat treatment. FIG. 4B is a cross-sectional view taken along the line I-I in FIG. In these drawings, 301 represents fine particles, and 302 represents a matrix component.

  FIG. 5A is a perspective view showing a state in which grooves formed in parallel to the incident direction of ions by irradiating a film made of the alignment film composition with an ion beam. Moreover, FIG.5 (b) is sectional drawing which follows the II-II line | wire of Fig.5 (a). As shown in these drawings, the groove 5 has a predetermined inclination angle in the longitudinal direction. Since the liquid crystal 6 is aligned in the uniaxial direction along the groove 5, it is possible to give a desired pretilt angle to the liquid crystal 6 according to this structure. Therefore, an alignment film suitable for an active element that drives liquid crystal in the polar angle direction can be obtained.

  On the other hand, FIG. 6A is a perspective view showing a state where grooves are formed perpendicular to the ion incident direction by irradiating a film made of the alignment film composition with an ion beam. Moreover, FIG.6 (b) is sectional drawing which follows the III-III line | wire of Fig.6 (a). In these figures, no anisotropy is observed in the longitudinal direction of the groove 5 '. Therefore, a pretilt angle cannot be given to the liquid crystal 6 ', and the alignment film is not suitable for an element that requires a pretilt angle. However, it can be a suitable alignment film for an element that does not require a pretilt angle, for example, an active element in an IPS (In-Plane Switching) mode. In the IPS mode, since the liquid crystal is driven in the azimuth direction, no pretilt angle is required. Rather, if the pretilt angle is zero, it is possible to obtain a good contrast by reducing the black luminance viewed from an arbitrary direction with a normally black type element. Therefore, in this case, it is considered that an alignment film having grooves formed perpendicular to the incident direction of the ion beam is preferably used. Further, when the pretilt angle is zero, the incident angle dependency is reduced, and therefore, it is preferably used for applications such as a wave plate. In the case of a wave plate having a pretilt angle, the phase difference obtained according to the incident angle is not symmetrical about 0 degree. For this reason, the dispersion | variation in a phase difference will become large depending on the arrangement | positioning method of a wavelength plate. On the other hand, if the pretilt angle is zero, a symmetrical phase difference can be obtained around 0 degree, so that the above problem can be solved. Accordingly, in this case, it is considered that an alignment film in which a groove is formed perpendicular to the incident direction of the ion beam is preferably used.

  The relationship between the ion incident direction and the groove forming direction is determined by the ion beam incident angle, the etching depth by the ion beam, and the like. Specifically, when the ion beam incident angle or ion dose changes, the etching direction changes between a direction perpendicular to the ion incident direction and a direction parallel to the ion incident direction. Such a phenomenon has been conventionally known, and Non-Patent Document 1 (Daiichiro Sekiba, “Pattern Formation on Metal Surface by Ion Sputtering”, Applied Physics, Vol. 73, No. 12 (2004), p. 1557), Non-Patent Document 2 (O. Yaroshchuk et al., “Planar and Tilted Uniform Alignment of Liquid Crystals by Plasma Treated Substrates”, electronic-liquid Crystal Communications, February 5, 2004, p. 1-22). Are listed.

For example, according to an experiment conducted by the present inventors, when an ion beam is irradiated with an energy of 500 eV on a SiONC film formed by a CVD method, the incident direction is smaller than 70 degrees when the incident angle is smaller than 70 degrees. However, when the incident angle is larger than 70 degrees, the groove is formed in parallel with the incident direction of ions. Thus, when the ion incident direction is brought close to the normal direction of the substrate, that is, when the incident angle is small, the direction of the groove is perpendicular to the ion incident direction. On the other hand, when the incident angle is increased and the incident direction of ions approaches a direction parallel to the substrate, the direction of the grooves becomes parallel to the incident direction of ions. Such transition of the groove formation direction is also caused when an ion beam is irradiated to a film obtained from an alignment film composition containing fine particles and a matrix component, or a film obtained from an alignment film composition consisting of fine particles and a solvent. It is thought to happen. That is, by making the ion beam obliquely enter these films, a groove parallel or perpendicular to the ion incident direction can be formed. Here, whether it is parallel or perpendicular depends on the incident angle and dose of ions.
When the incident angle is smaller than a predetermined value, a groove perpendicular to the ion incident direction is obtained, and this alignment film is suitable for an element that does not require a pretilt angle. On the other hand, when the incident angle is larger than a predetermined value, the groove becomes parallel to the incident direction of ions, and an alignment film suitable for an element requiring a pretilt angle can be obtained. The “predetermined value” at which the groove forming direction is changed from vertical to parallel differs depending on the type of material constituting the alignment film composition.

  An alignment film made of an inorganic material has a large effect due to the alignment of the liquid crystal grooves as described above. In order to improve the alignment regulating force of the alignment film, it is necessary to increase the alignment film anchoring energy. In general, it is known that the azimuth anchoring energy is expressed by the following equation (see Masaki Hasegawa, “Basics, Applications, and Processes of Liquid Crystal Orientation”, Tokyo Technical Information Service).

W _φ = (1/4) K ₁₁ (Aq) ² q
W _φ : Azimuth anchoring energy A: Groove depth q: Groove period K ₁₁ : Elastic constant for splay deformation

  From the above equation, it can be seen that the azimuth anchoring energy increases as the groove becomes deeper. Further, since the groove pitch (p) is expressed by p = 2π / q, the azimuth anchoring energy increases as the pitch decreases. Usually, the depth and pitch of the grooves formed on the surface of the thin film depend on the irradiation time and irradiation energy of the ion beam. That is, the longer the ion beam irradiation time and the larger the ion energy, the greater the depth of the groove. On the other hand, the groove pitch becomes finer as the ion beam irradiation time is shorter and the ion energy is smaller. To increase the anchoring energy, it is necessary to make the groove deeper or make the groove pitch finer. The effect of the ion beam irradiation time and irradiation energy on the groove depth and pitch is as described above. It will be in conflict. For this reason, for example, in the case of a SiONC film obtained by a CVD method, the groove pitch grows significantly when the groove is made deeper. However, the film obtained from an alignment film composition containing fine particles and a matrix component, or the film obtained from an alignment film composition consisting of fine particles and a solvent, suppresses the growth of the groove pitch compared to a film containing no fine particles. However, the depth of the groove can be increased. Here, when the etching rate of the matrix component is larger than that of the fine particles, it is preferable that at least the pitch of the grooves is about the average particle diameter of the fine particles from the viewpoint of the orientation regulating force.

In the present invention, the concave portion of the groove becomes a fine particle or a matrix component depending on which of the fine particles and the matrix component has a higher etching rate. Therefore, if this is utilized, the shape of the groove can be changed. That is, even if the materials have the same composition, the density of the fine particles and the matrix components changes with the change of the forming method, the forming conditions, or the structure, and the etching rate changes accordingly. For example, when SiO ₂ which is not hollow is used as the fine particles and tetraethoxysilane is used as the matrix component, the density of the matrix component is smaller, so that the concave portions are formed by etching faster than the fine particles. On the other hand, if the fine particles are hollow SiO ₂ , the fine particles are etched faster to form a recess. For example, when Ar ions having an energy of 500 eV and an ion density of 1 mA / cm ² are vertically incident on the substrate, the etching rates of SiO ₂ and Al ₂ O ₃ are 30 nm to 40 nm / min and 5 nm, respectively. ˜11 nm / min. Therefore, even when these materials are combined and a material having a high etching rate is used as the fine particles, the fine particles are etched faster than the matrix component to form a recess.

  The ion beam irradiation can be performed using, for example, an ion beam irradiation apparatus shown in FIG.

  In FIG. 7, a substrate holder 12 is provided in a chamber 11 in which ion beam irradiation is performed. A substrate 13 is set on the substrate holder 12. Here, a film (not shown) made of the alignment film composition after the heat treatment is formed on the substrate 13.

  The chamber 11 is equipped with an ion gun 14 and evacuated to a predetermined pressure by a vacuum pump (not shown) through an exhaust port 17. The ion gun 14 is provided with a gas inlet 15. The ions generated in the ion gun 14 are accelerated and aligned in direction by applying a voltage to the electrode system 16 to become an ion beam. In the present embodiment, the position of the substrate holder 12 is adjusted so that the ion beam is incident on the substrate 13 from the normal direction of the substrate 13 at a predetermined incident angle θ.

  Incidence angle θ needs to be an angle at which grooves are formed in parallel to the incident direction of ions in alignment films for applications that require a pretilt angle, and is further set appropriately according to the desired pretilt angle. Is done. Also, the ion beam irradiation time and irradiation energy affect the groove depth and pitch related to the azimuth anchoring energy, so the type and thickness of the alignment film composition, the pretilt angle value, and the required light resistance. It is preferable to set appropriately depending on the sex level.

  For example, the substrate 13 is set on the substrate holder 12, and the position of the substrate holder 12, that is, the incident angle θ is adjusted. θ is generally in the range of 40 degrees to 85 degrees. Next, the air in the chamber 11 is exhausted from the exhaust port 17 and the pressure is reduced to a predetermined pressure. Next, argon gas is introduced into the ion gun 14 through the gas inlet 15.

When the pressure of the introduced gas reaches about 1.0 × 10 ⁻³ Torr, discharge is performed to generate an ion beam. The acceleration voltage applied to the electrode system 16 is preferably 200V to 800V. The irradiation time of the ion beam is about 5 seconds to 120 seconds.

  As the ion gun, a Kaufmann type, a high-frequency type, or an ECR (electron cyclotron resonance) type capable of forming a large-diameter ion beam can be used. In addition, a neutralizing electron gun (Neutralizer) 18 is used to prevent the operation of the ion gun from becoming unstable due to charge-up on the surface of the substrate 13.

  As described above, in the present embodiment, an alignment film composition including fine particles and a matrix component having a higher etching rate by ion beam than the fine particles is applied onto a substrate, and the alignment film composition is applied to the alignment film composition. After the heat treatment is performed and the matrix component is polymerized, the ion beam is irradiated obliquely to the film made of the alignment film composition after the heat treatment. When a groove parallel to the ion incident direction is formed, the groove has a predetermined inclination angle with respect to the substrate. Therefore, by using the obtained alignment film, the liquid crystal can be aligned at a predetermined pretilt angle. On the other hand, when a groove perpendicular to the ion incident direction is formed, an alignment film suitable for an element that does not require a pretilt angle can be obtained.

  When the etching rate of the matrix component is larger than the fine particles, the pitch of the grooves formed on the surface of the alignment film is preferably substantially equal to the average particle diameter of the fine particles. Thereby, the alignment control force of the alignment film can be increased. Further, from the viewpoint of improving the light resistance of the alignment film, it is preferable to increase the proportion of fine particles in the alignment film composition.

In this embodiment, the alignment film composition is irradiated with an ion beam, but the present invention is not limited to this. In the present invention, a particle beam having a mass of about atoms and energy of about several tens eV to several hundreds eV can be used. Therefore, instead of the ion beam, for example, a plasma beam, an atomic beam, or a radical beam may be irradiated. However, in reality, it is difficult to irradiate a large area with an atomic beam or a radical beam with uniform and sufficient intensity (particles / cm ² · sec), and the apparatus becomes expensive and impractical. . For this reason, an ion beam or a plasma beam is preferably used. Further, it is preferable to irradiate a beam having good directivity in forming the groove. For this reason, the ion beam is more preferably used than the plasma beam.

  A liquid crystal optical element can be produced using the above-described method for producing an alignment film. The liquid crystal optical element may be either a horizontal alignment mode or a vertical alignment mode.

  Examples of the liquid crystal optical element include a liquid crystal lens element. By using the alignment film according to the present invention, a liquid crystal lens element having excellent optical characteristics and reliability can be obtained.

  FIG. 8 is an example of a schematic cross-sectional view of a liquid crystal lens element. As shown in this figure, the liquid crystal lens element 21 has a first transparent substrate 22 and a second transparent substrate 23 facing the first transparent substrate 22.

  A first electrode layer 24 and a first alignment film 25 are formed in this order on the first transparent substrate 22. On the other hand, a second electrode layer 26 and a second alignment film 27 are also formed in this order on the second transparent substrate 23. The first transparent substrate 22 and the second transparent substrate 23 are bonded to each other through a sealing material 28, and a liquid crystal layer 29 is filled between them to form a liquid crystal cell 30.

  The first electrode layer 24 and the second electrode layer 26 may be patterned concentrically, or may be formed in the surface shape of a concentric Fresnel lens body. However, one of these can be a solid electrode.

  The first alignment film 25 and the second alignment film 27 are alignment films formed by using the method according to the present invention.

  It is assumed that liquid crystal molecules having a positive dielectric anisotropy are used for the liquid crystal layer 29. However, liquid crystal molecules having negative dielectric anisotropy can also be used.

  The liquid crystal lens element 21 is a horizontal alignment mode in which the initial alignment state of liquid crystal molecules is substantially horizontal with respect to the substrate. When a voltage is applied to the first electrode layer 24 and the second electrode layer 26 via the power supply 31, the liquid crystal molecules are perpendicular to the first transparent substrate 22 and the second transparent substrate 23. Change direction. Then, with respect to incident light polarized in the direction of coordination of liquid crystal molecules, the apparent refractive index of the liquid crystal cell changes from a value for extraordinary light to a value for ordinary light. Thereby, the focal length of the liquid crystal lens element 21 can be changed from a value for abnormal light to a value for ordinary light.

  FIG. 9 is an example of a configuration diagram of an optical head device using the liquid crystal lens element 21 of FIG.

  In the optical head device 32 shown in FIG. 9, the light emitted from the light source 33 sequentially passes through the diffraction grating 34, the liquid crystal lens element 21, and the phase difference element 35, and then the optical disk 37 (or the optical disk 38) by the objective lens 36. It is focused on. Next, the light reflected by the optical disk 37 (or the optical disk 38) again passes through the objective lens 36, the phase difference element 35, and the liquid crystal lens element 21 in order, and is diffracted by the diffraction grating 34 to be detected by the photodetectors 39, 40. To reach.

  As the light source 33, an ordinary laser light source used in an ordinary optical head device is used. Specifically, a semiconductor laser is suitable, but other lasers may be used. If an inorganic material is used for the alignment film used in the liquid crystal lens element 21, excellent light resistance can be exhibited even when a blue laser (wavelength of 390 nm to 430 nm) is used as a light source.

  The diffraction grating 34 may be either a hologram or a beam splitter. When the beam splitter is used, the light path of the reflected light from the optical disk 37 (or the optical disk 38) is changed, and the light is guided to a photodetector (not shown) arranged in a direction different from the light source 33. Can do.

  A quarter wave plate is used as the phase difference element 35. Thereby, the polarization plane of the light from the light source 33 and the return light from the optical disk 37 (or the optical disk 38) can be changed by rotating the polarization plane of the light.

  The liquid crystal lens element 21 can change the focal length according to the presence or absence of voltage application. Therefore, for example, when the voltage is not applied to the liquid crystal lens element 21, the optical disk 37 is focused, and when the voltage is applied to the liquid crystal lens element 21, the optical disk 38 is focused. Can be. Further, when the voltage is not applied to the liquid crystal lens element 21, the optical disk 38 is focused. When the voltage is applied to the liquid crystal lens element 21, the optical disk 37 is focused. You can also.

  Since the above optical head device uses a liquid crystal lens element having an alignment film with high alignment regulation power and excellent reliability, it can have both excellent optical characteristics and high reliability.

  Furthermore, another optical head device obtained by using the method for producing an alignment film according to the present invention will be described.

  FIG. 10 is another example of a configuration diagram of the optical head device according to the present embodiment.

  In the optical head device 41 shown in FIG. 10, the light emitted from the semiconductor laser 42 is converted into parallel light by the collimator lens 43 and then transmitted through the liquid crystal element 44. Here, a voltage can be applied to the liquid crystal element 44 from the outside by a voltage control device 45. The light transmitted through the liquid crystal element 44 is transmitted through the polarizer 46 and the λ / 4 plate 47 and then condensed on the optical recording medium 50 by the condenser lens 49 mounted on the actuator 48.

  The polarizer 46 changes the amount of light emitted toward the optical recording medium 50 according to the polarization direction of the incident light when light incident on the polarizer 46 is emitted. In the example of FIG. 10, a polarizing beam splitter is used as the polarizer 46. However, for example, a diffraction grating including a prism or a wire grating can also be used. Further, the polarizer 46 may be integrated by being attached to a transparent substrate (not shown) on the condenser lens 49 side of the liquid crystal element 44.

  The light reflected by the optical recording medium 50 travels in reverse on the above optical path. In the example of FIG. 10, since a polarizing beam splitter is used for the polarizer 46, the light traveling in the reverse direction of the optical path is reflected by the polarizer 46 and then condensed by the condenser lens 51 to the photodetector 52. To reach. At this time, when a plurality of different voltages are applied to the liquid crystal element 44, the polarization direction of the light transmitted through the liquid crystal element 44 changes, and the amount of light transmitted through the polarizer 46 and condensed on the optical recording medium 50 can be changed. .

  Since the amount of light emitted from the semiconductor laser 42 is changed by passing through the polarizer 46, the light needs to pass through the liquid crystal element 44 before passing through the polarizer 46 in the forward path. That is, it is necessary to dispose the liquid crystal element 44 on the semiconductor laser 42 side with respect to the polarizer 46 on the optical path.

  FIG. 11 is a schematic cross-sectional view of the liquid crystal element 44. As shown in this figure, the liquid crystal element 44 is formed on transparent substrates 61 and 62, transparent electrodes 64 and 65 that are formed on these surfaces and apply a voltage to the liquid crystal layer 63, and transparent electrodes 64 and 65. The alignment films 66 and 67 are formed. The transparent substrates 64 and 65 are bonded together with a sealing material 69. The alignment films 66 and 67 are alignment films formed using the method according to the present invention. The liquid crystal constituting the liquid crystal layer 63 can be, for example, a twisted nematic liquid crystal. Then, grooves parallel to the ion incident direction are formed on the surfaces of the alignment films 66 and 67 so that the liquid crystal molecules 68 are given a predetermined pretilt angle (for example, 0 degree <pretilt angle <5 degrees). ing.

  The alignment direction of the liquid crystal molecules 68 at the boundary surface between the two transparent substrates 61 and 62 and the liquid crystal layer 63 is substantially horizontal with respect to the transparent substrates 61 and 62 although it is inclined by a predetermined pretilt angle. . Further, these orientation directions form an angle with each other. Therefore, the major axis direction of the liquid crystal molecules 68 has a structure in which the liquid crystal molecules 68 are continuously twisted around the axis in the thickness direction of the liquid crystal layer 63 between the transparent substrates 61 and 62.

  For example, the optical head device 41 is arranged so that the polarization direction of the incident light to the liquid crystal element 44 matches the alignment direction of the liquid crystal molecules 68 on the transparent substrate 61 on the semiconductor laser 42 side of the liquid crystal element 44. At this time, the alignment direction of the liquid crystal molecules 68 between the two transparent substrates 61 and 62 is twisted by a predetermined angle (for example, 45 degrees) horizontally with respect to the substrate surface. On the other hand, the transmission axis direction of the polarizer 46 coincides with the polarization direction of the semiconductor laser 42. When a voltage is applied to the liquid crystal element 44, the alignment direction of the liquid crystal molecules 68 is aligned with the electric field direction, so that the light from the semiconductor laser 42 passes through the liquid crystal element 44 without changing the polarization direction. Then, the light passes through the polarizer 46 as it is.

  When no voltage is applied, the polarization direction of the light from the semiconductor laser 42 transmitted through the liquid crystal element 44 is changed by taking an arrangement in which the major axis direction of the liquid crystal molecules 68 is twisted. For this reason, the amount of light transmitted through the polarizer 46 is reduced by deviating from the transmission axis direction of the polarizer 46. Therefore, by adjusting the voltage applied to the liquid crystal element 44, it is possible to adjust the amount of light transmitted through the polarizer 46 without changing the output of the semiconductor laser 42.

  Since the optical head device 41 uses the alignment films 66 and 67 obtained by the present invention for the liquid crystal element 44, it can have both excellent optical characteristics and high reliability. For example, when a polyimide film is used as the alignment film, the required light resistance cannot be obtained in applications using a blue laser (wavelength 390 nm to 430 nm) as a light source. On the other hand, the alignment film obtained by the present invention, particularly an alignment film using an inorganic material, can provide better light resistance than polyimide.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, an alignment film composition containing fine particles and a matrix component is used. However, the present invention is not limited to this, and a material comprising fine particles and a solvent can also be used as the alignment film composition. That is, the alignment component may not contain a matrix component. Specifically, after an alignment film composition comprising fine particles and a solvent is applied on a substrate, the alignment film composition is subjected to a heat treatment to remove the solvent. Next, an ion beam is obliquely incident on the alignment film composition after the heat treatment, thereby forming grooves parallel or perpendicular to the incident direction of ions on the surface of the alignment film composition. Also by this method, it is possible to obtain an alignment film excellent in alignment regulating force and light resistance.

  Examples of the present invention will be described below.

Example 1
<Alignment film composition>
As a raw material for fine particles, a dispersion of SiO ₂ (product name: IPA-ST, manufactured by Nissan Chemical Industries, Ltd.) having an average particle diameter of 10 nm to 15 nm (catalog value, measurement is according to the BET method) was used. Further, a solution containing 17.4% by mass of tetraethoxysilane, 26.9% by mass of water, 55.5% by mass of an alcohol solvent and 0.2% by mass of nitric acid (61%) as a catalyst was prepared, and a raw material for the matrix component It was. Here, as the alcohol solvent, a mixture of 85.5% by mass of ethyl alcohol, 9.8% by mass of isopropyl alcohol, and 4.7% by mass of methyl alcohol was used.

The fine particle raw material and the matrix component raw material were mixed so that the fine particles were present at a ratio of 80% by mass with respect to the total amount of the SiO ₂ mass in the fine particle raw material and the SiO ₂ converted mass of the matrix component raw material. after all SiO ₂ component was diluted with ethyl alcohol to be 5 mass%, and an alignment film composition. The SiO ₂ equivalent mass of the matrix component raw material was determined from a tetraethoxysilane precursor.

<Formation of alignment film>
As a substrate, a quartz substrate having a thickness of 0.525 mm in which an ITO film and an insulating film were provided in this order on one main surface was prepared. Then, the alignment film composition was applied to the surface of the substrate on which the ITO film was provided by a spin coating method (rotation speed: 2500 rpm). Then, after pre-baking for 1 minute at 85 degreeC, it post-baked for 30 minutes at 400 degreeC, and the thin film whose film thickness is about 120 nm was formed.

The obtained thin film was irradiated with an Ar ion beam from a direction oblique to the substrate. The pressure in the chamber was 1.3 × 10 ⁻¹ Pa, the incident angle of the ion beam was 80 degrees from the normal direction of the substrate, the ion energy was 500 eV, and the irradiation time was 60 seconds.

  FIG. 12A is an SEM photograph of a thin film formed using the alignment film composition before ion beam irradiation. FIG. 12B is an SEM photograph of the alignment film obtained by ion beam irradiation. Individual particles can be clearly recognized before ion beam irradiation. However, it can be seen that when the ion beam is irradiated, the appearance is clearly different from that before irradiation, and the fine particles are connected in the ion incident direction.

<Production of liquid crystal cell>
Two substrates with an alignment film produced as described above were superposed and bonded via a sealant. Specifically, one substrate is screen-printed with a sealing material (thermosetting epoxy resin) filled with a 5 μm spacer, and the direction of orientation treatment between this substrate and the other substrate (that is, the incident direction of ions). However, the orientation was determined so as to form an angle of 45 degrees (45 degree twist orientation), and the films were bonded together. At this time, the surfaces on which the alignment films are formed face each other inward, and an opening that can be filled with liquid crystal from the outside is provided.

  Next, a liquid crystal for horizontal alignment (manufactured by Dainippon Ink Co., Ltd., trade name: RDP94024) was injected between the two substrates through the opening by a vacuum injection method. Next, the opening was sealed with a sealing material (photocurable acrylic resin) to obtain a liquid crystal cell. The liquid crystal cell was heated for 10 minutes at a temperature at which the liquid crystal was in an isotropic phase and then slowly cooled to rearrange the liquid crystal.

  A polarizer and an analyzer are bonded to this liquid crystal cell so that they are crossed Nicols so that the polarization direction of the incident light coincides with the major axis direction of the liquid crystal on the incident surface of the liquid crystal cell. Then, when the alignment of the liquid crystal was observed without applying a voltage, it was confirmed that the alignment state of the liquid crystal was generally good.

<Evaluation of orientation regulation power>
In order to evaluate the alignment regulating force of the obtained alignment film, the twist angle of the liquid crystal cell was measured, and the value was 39.6 degrees with respect to the design value of 45 degrees (see FIG. 13). .
For the measurement, an ellipsometer manufactured by Shintech Co., Ltd. (product name: OPTIPRO) was used.

<Evaluation of light resistance>
In order to evaluate the light resistance of the liquid crystal cell, the change rate of the twist angle with respect to the integrated light amount was examined. The results are shown in FIG. In the evaluation, after irradiating the liquid crystal cell with light of a blue laser diode (wavelength: 405 nm) at an irradiation density of 20 mW / mm ² , the twist angle is measured with an ellipsometer (product name: OPTIPRO) manufactured by Shintech Co., Ltd. Was done. Also, the twist angle change rate = (twist angle after laser light irradiation / twist angle before laser light irradiation).

As is clear from FIG. 14, even when the integrated light amount was 35 Wh / mm ² , no significant change in the twist angle was observed. From this, it was found that the liquid crystal maintained the same alignment state as at the start of the test and had good light resistance.

Example 2
As a raw material for fine particles, a dispersion of SiO ₂ (product name: IPA-ST-MS, manufactured by Nissan Chemical Industries, Ltd.) having an average particle diameter of 17 nm to 23 nm (catalog value, measurement is according to the BET method) was used. A liquid crystal cell was produced in the same manner as in Example 1 except for the above. With respect to this liquid crystal cell, the twist angle was measured in the same manner as in Example 1. The value was 41.8 degrees with respect to the design value of 45 degrees (see FIG. 13).

Example 3
As a raw material of fine particles, a dispersion of SiO ₂ (product name: IPA-ST-L, manufactured by Nissan Chemical Industries, Ltd.) having an average particle size of 40 nm to 50 nm (catalog value, measurement is according to the BET method) was used. A liquid crystal cell was produced in the same manner as in Example 1 except for the above. When the twist angle of this liquid crystal cell was measured in the same manner as in Example 1, the value was 37.8 degrees with respect to the design value of 45 degrees (see FIG. 13).

Example 4
As a raw material for fine particles, a dispersion of SiO ₂ (product name: IPA-ST-ZL, manufactured by Nissan Chemical Industries, Ltd.) having an average particle size of 70 nm to 100 nm (catalog value, measured by BET method) was used. A liquid crystal cell was produced in the same manner as in Example 1 except for the above. With respect to this liquid crystal cell, the twist angle was measured in the same manner as in Example 1. The value was 32.5 degrees with respect to the design value of 45 degrees (see FIG. 13).

  A polarizer and an analyzer are bonded to this liquid crystal cell so that they are crossed Nicols so that the polarization direction of the incident light coincides with the major axis direction of the liquid crystal on the incident surface of the liquid crystal cell. Then, when the alignment of the liquid crystal was observed without applying a voltage, it was confirmed that the alignment state of the liquid crystal was generally good.

Example 5
Except for mixing the fine particle raw material and the matrix component raw material so that the fine particles are present in a ratio of 60% by mass with respect to the total amount of the SiO ₂ mass in the fine particle raw material and the SiO ₂ equivalent mass of the matrix component raw material. A liquid crystal cell was produced in the same manner as in Example 1. With respect to this liquid crystal cell, the twist angle was measured in the same manner as in Example 1. The value was 38.3 degrees with respect to the design value of 45 degrees (see FIG. 13). The light resistance was evaluated in the same manner as in Example 1.
The results are shown in FIG.

From FIG. 14, it was found that the change rate of the twist angle up to the integrated light amount of 35 Wh / mm ² was the same as in Example 1, and had good light resistance.

Example 6
Except for mixing the fine particle raw material and the matrix component raw material so that the fine particles are present in a ratio of 40% by mass with respect to the total amount of the SiO ₂ mass in the fine particle raw material and the SiO ₂ equivalent mass of the matrix component raw material. A liquid crystal cell was produced in the same manner as in Example 1. With respect to this liquid crystal cell, the twist angle was measured in the same manner as in Example 1. The value was 37.0 degrees with respect to the design value of 45 degrees (see FIG. 13). The light resistance was evaluated in the same manner as in Example 1.
The results are shown in FIG.

As shown in FIG. 14, the change rate of the twist angle increased as the integrated light amount increased. From this result, it was found that the light resistance improves as the proportion of fine particles in the alignment film composition increases.
Also in this example, the twist angle at the time of cell formation is closer to the design value of 45 degrees than that containing fine particles having an average particle diameter larger than 70 nm or not containing fine particles described later, and the fine particles were used. As a result, the effect of improving the alignment control power was confirmed. The configuration of the present embodiment is suitable for uses other than those using a blue laser (wavelength 390 nm to 430 nm) as a light source.

Example 7
As the alignment film composition, a dispersion of SiO ₂ fine particles (trade name: Ceramate LNT, manufactured by Catalyst Kasei Kogyo Co., Ltd.) commercially available in a state where fine particles and a matrix component are mixed was used. The average particle size of the fine particles was 25 nm (catalog value). Next, propylene glycol monopropyl ether was added to the dispersion to a concentration of 20% by mass, and the mixture was stirred for 10 minutes at 300 rpm and mixed.

  As a substrate, a quartz substrate having a thickness of 0.525 mm in which an ITO film and an insulating film were provided in this order on one main surface was prepared. Then, the alignment film composition was applied to the substrate surface on which these films were provided by a spin coating method (rotation number: 1500 rpm). Then, after prebaking at 120 ° C. for 120 minutes, post baking was performed at 400 ° C. for 30 minutes to form a thin film having a thickness of about 100 nm.

  FIG. 15A is an SEM photograph of a thin film formed using the alignment film composition before ion beam irradiation. FIG. 15B is an SEM photograph of the alignment film obtained by ion beam irradiation. Individual particles can be clearly recognized before ion beam irradiation. However, it can be seen that when the ion beam is irradiated, the appearance is clearly different from that before irradiation, and the fine particles are connected in the ion incident direction.

  After the formation of the thin film, an alignment film was formed in the same manner as in Example 1, and a liquid crystal cell was produced using the alignment film.

  A polarizer and an analyzer are bonded to this liquid crystal cell so that they are crossed Nicols so that the polarization direction of the incident light coincides with the major axis direction of the liquid crystal on the incident surface of the liquid crystal cell. Then, when the alignment of the liquid crystal was observed without applying a voltage, it was confirmed that the alignment state of the liquid crystal was generally good.

  About the obtained liquid crystal cell, it carried out similarly to Example 1, and evaluated the alignment control force of the alignment film and the light resistance of the liquid crystal cell. As a result, the value of the twist angle was 40.6 degrees with respect to the design value of 45 degrees (see FIG. 13). Further, the light resistance was as shown in FIG. That is, the change rate of the twist angle increased with an increase in the integrated light amount.

  When the alignment film composition used is observed with an SEM, it appears that the ratio of the matrix component is large. For this reason, like Example 6, it seems that it became a result inferior to light resistance compared with Example 1 and 5 with many ratios of microparticles | fine-particles. Also in this example, the twist angle at the time of cell formation was closer to the design value of 45 degrees than that which does not contain fine particles described later, and the effect of improving the alignment regulating force by using fine particles could be confirmed. . The configuration of the present embodiment is suitable for uses other than those using a blue laser (wavelength 390 nm to 430 nm) as a light source.

Example 8
As a raw material for fine particles, a dispersion of SiO ₂ (product name: IPA-ST, manufactured by Nissan Chemical Industries, Ltd.) having an average particle size of 10 nm to 15 nm (catalog value, measurement is according to the BET method) is used. The alignment film composition was prepared by diluting with ethyl alcohol so that the SiO ₂ component in the solution was 5% by mass.

  A liquid crystal cell was produced in the same manner as in Example 1 using the alignment film composition. When the twist angle of this liquid crystal cell was measured in the same manner as in Example 1, the value was 43.1 degrees with respect to the design value of 45 degrees (see FIG. 13), which is very close to the design value. It was.

Example 9
As a raw material for fine particles, a dispersion of SiO ₂ (hereinafter referred to as surface-modified SiO ₂ ) having an average particle size of 15 nm to 20 nm (catalog value) in which silanol groups on the fine particle surface are substituted with organic groups (hereinafter referred to as “surface modified SiO ₂ ”) The product of the company, trade name: Quarton PL-2L-IPA), the fine particle raw material and the matrix component raw material, the mass of the surface modified SiO ₂ (including organic groups) in the fine particle raw material, and the matrix component raw material SiO ₂ A liquid crystal cell was produced in the same manner as in Example 1 except that mixing was performed so that the fine particles were present at a ratio of 80% by mass with respect to the total amount with the converted mass. When the twist angle of this liquid crystal cell was measured in the same manner as in Example 1, the value was 42.7 degrees with respect to the design value of 45 degrees (see FIG. 13).

<Reliability evaluation>
In order to evaluate the reliability of the liquid crystal cell, the change rate of the twist angle after a 168 hour high temperature and high humidity environment test (65 ° C., 95% RH) was examined. The results are shown in FIG. The evaluation was performed by measuring the twist angle with an ellipsometer (product name: OPTIPRO) manufactured by Shintech Co., Ltd. Further, the change rate of the twist angle = (twist angle after the high temperature and high humidity environment test / twist angle before the high temperature and high humidity environment test).

  As is clear from FIG. 16, even after the 168 hour high-temperature and high-humidity environment test (65 ° C., 95% RH), no significant change in the twist angle was observed. From this, it was found that the liquid crystal maintained the alignment state similar to that at the start of the test and had good reliability.

Comparative Example 1
A liquid crystal cell was prepared in the same manner as in Example 1 except that the alignment film composition was a fine particle raw material and the matrix component was diluted with ethyl alcohol so that the concentration in terms of SiO ₂ was 5% by mass. Was made. The concentration obtained by converting the matrix component to SiO ₂ was determined from a precursor of tetraethoxysilane. When the twist angle of the obtained liquid crystal cell was measured in the same manner as in Example 1, the value was 31.1 degrees with respect to the design value of 45 degrees (see FIG. 13).

  From this result, it was found that the alignment film composition containing fine particles has a twist angle closer to the design value and exhibits a higher alignment regulating force.

Comparative Example 2
Instead of forming a thin film using the alignment film composition as in Examples 1 to 7 and Comparative Example 1, a SiO ₂ film having a thickness of about 200 nm was formed on the substrate by sputtering. Otherwise, a liquid crystal cell was produced in the same manner as in Example 1. When the twist angle of this liquid crystal cell was measured in the same manner as in Example 1, the value was 19.5 degrees with respect to the design value of 45 degrees (see FIG. 13).

Comparative Example 3
Instead of forming a thin film using the alignment film compositions as in Examples 1 to 7 and Comparative Example 1, a SiON film having a thickness of about 200 nm was formed on the substrate by sputtering. Otherwise, a liquid crystal cell was produced in the same manner as in Example 1. When the light resistance of this liquid crystal cell was evaluated in the same manner as in Example 1, a change as shown in FIG. 14 was observed. That is, the change rate of the twist angle when the integrated light amount was 5 Wh / mm ² was larger than that in Example 7. Moreover, since the change of the external appearance was also large, the test was stopped at this point.

Comparative Example 4
A particulate material and a matrix ingredient material, and SiO ₂ mass in the microparticles raw material, the total amount of SiO ₂ reduced mass of the matrix ingredient material, except that the fine particles are mixed to be present in a proportion of 30% by weight A liquid crystal cell was produced in the same manner as in Example 1. When the twist angle of this liquid crystal cell was measured in the same manner as in Example 1, the value was 29.7 degrees with respect to the design value of 45 degrees (see FIG. 13).

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application 2007-170507 filed on June 28, 2007 and Japanese Patent Application 2007-300408 filed on November 20, 2007, the contents of which are incorporated herein by reference.

  The alignment film obtained by the present invention is applied to, for example, personal computers, game devices, information terminal devices, instruments such as vehicles, digital cameras, video cameras, printers or optical communication devices, or projector-related components. Can do. In particular, since projector-related parts are required to have very strong light resistance, an alignment film obtained by the present invention, particularly an alignment film using an inorganic material is preferable.

Claims (13)

Applying an alignment film composition including fine particles and matrix components having different fine particles and an ion beam or plasma beam etching rate on a substrate;
A step of performing a heat treatment on the alignment film composition to advance polymerization of the matrix component;
A step of forming grooves parallel or perpendicular to the incident direction of the beam on the surface of the film made of the alignment film composition by obliquely making the beam incident on the film made of the alignment film composition after the heat treatment A method for producing an alignment film, comprising:   The method for producing an alignment film according to claim 1, wherein the alignment film composition contains the fine particles as a main component.   The method for producing an alignment film according to claim 1, wherein the matrix component has an etching rate larger than that of the fine particles, and the pitch of the grooves is substantially equal to an average particle diameter of the fine particles. The matrix component includes Ca, Li, Al, Mg, Ce, Si, Sn, Y, Hf, Zr, Zn, Ta, Ti, CaF ₂ , LiF, AlF ₃ , MgF ₂ , CeF ₃ , Al ₂ O ₃ , It contains SiO ₂ , SnO ₂ , MgO, Y ₂ O ₃ , HfO ₂ , ZrO ₂ , ZnO, Ta ₂ O ₅ , CeO ₂ , Nb ₂ O ₅ , TiO, TiO ₂ or ITO as a constituent component. The manufacturing method of the orientation film of any one of Claims 1-3. Applying an alignment film composition comprising fine particles and a solvent on a substrate;
Performing a heat treatment on the alignment film composition to remove the solvent;
By making an ion beam or a plasma beam obliquely enter the film made of the alignment film composition after the heat treatment, grooves parallel or perpendicular to the incident direction of the beam are formed on the surface of the film made of the alignment film composition. And a step of forming the alignment film.   6. The method for producing an alignment film according to claim 5, wherein a pitch of the grooves is substantially equal to an average particle diameter of the fine particles.   The method for producing an alignment film according to claim 1, wherein an average particle diameter of the fine particles is 70 nm or less. The fine particles, Ca, Li, Al, Mg , Ce, Si, Sn, Y, Hf, Zr, Zn, Ta, Ti, CaF 2, LiF, AlF 3, MgF 2, CeF 3, Al 2 O 3, SiO ₂ , SnO ₂ , MgO, Y ₂ O ₃ , HfO ₂ , ZrO ₂ , ZnO, Ta ₂ O ₅ , CeO ₂ , Nb ₂ O ₅ , TiO, TiO ₂ or ITO. 8. A method for producing an alignment film according to any one of 7 above. Applying an alignment film composition comprising fine particles of SiO ₂ and a matrix component of tetraethoxysilane on a substrate;
A step of performing a heat treatment on the alignment film composition to advance polymerization of the matrix component;
By making an ion beam or a plasma beam obliquely enter the film made of the alignment film composition after the heat treatment, grooves parallel or perpendicular to the incident direction of the beam are formed on the surface of the film made of the alignment film composition. And forming a process,
The method for producing an alignment film, wherein the fine particles are present in the alignment film composition in a proportion of 40% by mass or more based on a total amount of the mass of the fine particles and the mass of the matrix component in terms of SiO ₂ .   The method for producing an alignment film according to claim 9, wherein the matrix component has an etching rate faster than the fine particles, and the pitch of the grooves is substantially equal to an average particle diameter of the fine particles.   The method for producing an alignment film according to claim 9 or 10, wherein an average particle diameter of the fine particles is 70 nm or less.   The liquid crystal optical element provided with the orientation film manufactured by the method of any one of Claims 1-11.   An optical head device comprising the liquid crystal optical element according to claim 12.

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