JP2011107601A - Light projection exposure apparatus by stereoscopic projection, and light projection exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transfer a fine concavo-convex structure onto a three-dimensional surface such as a cylinder face, the structure having no seam in the circumference direction and continuing in the axial direction. <P>SOLUTION: A pattern on a mask is transferred onto a surface of a three-dimensional structure as an axially endless pattern without seam by irradiating a planar photomask face having a predetermined mask pattern with light, reflecting the transmitted light on a three-dimensional reflection mirror having a conical opening, irradiating a photosensitive material applied on the surface of the three-dimensional structure with the reflected light for exposure, and intermittently supplying the three-dimensional structure. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photolithography method for transferring a fine pattern by light irradiation on the surface of a photosensitive material, and more particularly to a light projection exposure apparatus and a light projection exposure method for transferring a pattern to the surface of a three-dimensional structure. It is.

The microfabrication technology based on the Si substrate has been developed as a method for processing a circuit pattern on a plane mainly in the manufacture of semiconductor elements and optical elements.
However, the demand for microfabrication technology has begun to spread in various fields, the substrate material has been diversified from Si, and the shape of the device has also changed from a plane to a solid. For example, Non-Patent Document 1 discloses a process for producing a TiNi shape memory alloy actuator by transferring a mesh pattern to a surface of a copper cylinder having a diameter of 3 mm on which a TiNi thin film is formed by light exposure.

In addition, examples of the development of high-frequency microcoils by transferring a spiral groove with a width of 10 μm onto a brass cylinder surface having a diameter of 0.5 mm coated with an X-ray photosensitive material using X-rays having a short wavelength are described below. This is disclosed in Patent Document 2.
Further, the following Non-Patent Document 3 discloses an example in which a semiconductor device such as a thin film transistor (TFT) or an organic light emitting diode (OLED) is processed using a 200 μm square quartz fiber as a base material to develop a fiber-shaped device. .

The technique of performing microfabrication on a cylindrical surface can be used not only for device development but also as a method for producing a roll-to-roll imprint cylindrical mold. In roll-to-roll imprinting, a molded substrate is held at a glass transition temperature or lower, a cylindrical mold is heated to a temperature higher than the glass transition temperature of a molding material, and a concavo-convex pattern on the mold is transferred while rotating. In roll-to-roll imprinting, continuous transfer onto a sheet-like molding material with no length limitation is possible, and it is expected as the ultimate technique for increasing the area in nanoimprinting.
As disclosed in Non-Patent Documents 4 and 5 below, the cylindrical mold is produced by a method in which a Ni film having a thickness of 100 μm is wound around a cylindrical surface that has been surface polished, or a pattern is machined directly on a metal cylindrical surface. There is a technique to do.

  In addition, as another related art, Patent Document 1 discloses that an optical fiber having an incident end face with an inclination angle is rotated about the optical axis, and a laser beam is irradiated on the entire surface of a spherical irradiated object by a spheroid mirror. It is possible to process and manufacture an integrated circuit into a spherical shape by this, and in Patent Document 2, it is possible to form an image by geometrically converting a drawing pattern on the surface of an object onto a cylindrical outer surface by a cone lens and an aperture stop. Further, Patent Document 3 describes that a fine protrusion pattern or a fine hole array pattern is formed seamlessly on the surface of a roll-shaped mold to increase the imprint area.

Japanese Patent Application Laid-Open No. 11-11609 Japanese Patent Laid-Open No. 10-186236 JP 2008-229869 A

Takashi Hamada. Other, IEEJ Transactions E, vol. 123, p. 158 (2003) H. Mekaru et al. , Jpn. J. et al. Appl. Phys. , Vol. 43, p. 4036 (2004) Y. Sugawara et al. , Appl. Phys. Lett. , Vol. 91, p. 203518-1 (2007) H. Tan et al. , J .; Vac. Sci. Technol. B, vol. 16, p. 3926 (1998) S. Ahn et al. , Proc. NNT2006, p. 203 (2006)

However, any prior art does not consider the seam when the cylindrical mold rotates once in the circumferential direction. The TiNi actuator and the high-frequency microcoil described above have an advanced alignment function so that the pattern of the flat mask is projected onto the cylindrical surface by light or X-ray as shown in FIG. It is given to the exposure apparatus.
For this reason, it is not a process that can be widely applied to patterns of arbitrary shapes.

  As a method of transferring a pattern onto a three-dimensional surface by projecting ultraviolet rays, a method of collectively irradiating the spherical surface using an optical fiber and a spheroid mirror is disclosed in Patent Document 1. The light obliquely incident on the optical fiber from the beam converter is emitted from one focal point of the spheroid mirror, reflected by the surface of the spheroid mirror, and then the spherical irradiated object disposed at the other focal point of the spheroid mirror. The entire surface is irradiated.

  However, this method is not suitable for a cylindrical surface because it is an exposure method that matches a spherical surface. Furthermore, the pattern cannot be transferred because it does not go through a mask. If patterning is performed by pulsing the light source, the surface of the three-dimensional irradiation object must be scanned in accordance with the pattern shape, and eventually pattern transfer cannot be performed.

  As a method for transferring a pattern onto a cylindrical surface through a mask, an exposure method using a cone lens and an aperture stop in combination is disclosed in Patent Document 2. However, since a part of the cylindrical surface is sequentially exposed while rotating the aperture stop having the slit structure, the pattern cannot be transferred at once. Further, the light patterned by the mask must pass through the rotation center axis of the aperture stop before entering the cone lens, and there is a physical restriction on the length of the cylindrical substrate that can be exposed.

  Problems that cannot be realized by batch pattern transfer can also be pointed out by micromachining by machining. As a precision machining technique, a spiral groove having a pattern width of 10 μm is formed on a cylindrical surface having a diameter of 0.5 mm by using a high precision cutting tool and a 5-axis driven nanoprocessor. However, the cutting material is limited to relatively soft metals such as Ni—P alloy, Cu, and Al due to the wear of the cutting tool.

  In addition, there is a processing example of a cylindrical mold for gravure printing by direct drawing of an Ar laser as shown in FIG. 1B, but processing is performed with high accuracy by synchronizing rotation and feed of a processing target such as a spiral groove. This is difficult, and the minimum processing dimension is comparatively large at 20 μm, and cannot be used for a cylindrical mold for nanoimprinting. In any case, the precision machining method and the laser drawing method have a disadvantage that the cutting surface needs to be scanned with a cutting tool or a laser according to the pattern, and the processing time is relatively long.

  In research on seamless machining of cylindrical molds, porous alumina is formed on the surface of an Al cylinder as disclosed in Patent Document 3 in addition to the direct drawing method such as one-stroke drawing using a nanoprocessor or Ar laser. However, there is a case where a cylindrical Ni electroforming mold is produced by a mold process. However, although a certain degree of regularity can be obtained by optimizing the conditions, porous alumina can only form a pillar structure because it uses a natural phenomenon, and the position and shape of the pattern are not arbitrary. Therefore, the application field is limited to an antireflection film and the like, and industrial versatility is low.

  A micro uneven structure of an arbitrary shape is processed at an arbitrary position on a three-dimensional surface such as a cylindrical surface at a high speed by batch transfer, and when the three-dimensional structure is rotated once in the circumferential direction, a seamless seamless finish is given. This is not possible with existing technology.

  For example, an active catheter that is currently being researched to enable smooth insertion into the body (a microactuator is mounted on the tip so that the tip can be moved actively, and its movement can be controlled freely from outside the body. If the control device, the actuator, the signal circuit, etc. can be formed seamlessly and in the axially continuous pattern on the outer peripheral surface of the tubular catheter, the performance can be dramatically improved. .

  Therefore, in view of the above-mentioned disadvantages of the prior art, the present invention provides a photostereoscopic projection exposure method in order to form a fine uneven structure that is seamless and continuous in the axial direction on a three-dimensional surface such as a cylindrical surface in a short process time. Therefore, when the three-dimensional structure is rotated once in the circumferential direction, the pattern transfer that is seamless and continuous in the axial direction is performed indefinitely.

  In order to achieve this object, according to the light projection exposure apparatus of the present invention, light is irradiated onto a flat photomask surface having a predetermined pattern on the mask surface, and the transmitted light is formed into a mortar-shaped opening hole. The light is reflected by the three-dimensional reflection type mirror, and is applied to the photosensitive material applied to the surface of the three-dimensional structure, and the three-dimensional structure is intermittently supplied to the surface of the three-dimensional structure. The pattern on the mask surface is transferred as a seamless pattern that is continuous in the axial direction.

  This flat type photomask has a pattern in which a plurality of closed curves that do not intersect with each other and a connecting portion that connects two adjacent closed curves are combined, and includes a portion that transmits light and a portion that blocks light. It is desirable to be able to align with a three-dimensional structure coated with a photosensitive material.

  Further, in the above light projection exposure apparatus, the light irradiated on the flat photomask surface is radiated from the light generator, and then collimated, focused or diffused by the lenses arranged before and after the flat photomask. It may be made to be.

  In addition, the three-dimensional reflection type mirror has a mortar-shaped opening hole in a metal or glass material, and its inner peripheral wall section has a straight or curved surface. In the case of a glass substrate, it reflects light on the inner peripheral wall. It may be formed by coating the material to be used.

  This three-dimensional reflection type mirror reflects the light transmitted through the flat plate photomask as either parallel light, focused light, or divergent light depending on the cross-sectional shape of its inner peripheral wall, and the pattern on the mask surface is scaled or reduced. Alternatively, it is desirable to enlarge the photosensitive material applied to the surface of the three-dimensional structure so as to be exposed.

  Furthermore, according to the light projection exposure method of the present invention, the step of positioning a flat plate photomask having a predetermined pattern on the mask surface, and the inside of the three-dimensional reflection type mirror having a mortar-shaped opening hole, The step of positioning the three-dimensional structure coated with the photosensitive material, the step of irradiating light on the surface of the flat photomask, and the three-dimensional structure reflecting the transmitted light by a three-dimensional reflection mirror A step of exposing a photosensitive material applied to the surface of the substrate and a step of intermittently supplying the positioned three-dimensional structure, and the pattern on the mask surface is a seamless pattern that is continuous in the axial direction. Can be transferred as.

  As described above, according to the present invention, for example, a three-dimensional surface such as a cylindrical surface is seamless in the circumferential direction by optical three-dimensional exposure using a three-dimensional reflection type mirror having a mortar-shaped opening hole, In addition, it is possible to realize transfer of a fine concavo-convex structure that is continuous indefinitely in the axial direction.

It is a figure which shows the transfer method of the fine pattern to the conventional three-dimensional structure surface. It is a figure which shows the transfer principle of the fine pattern to the surface of a three-dimensional structure by a three-dimensional projection exposure method. It is a figure which shows the transfer method of the continuous fine pattern by the three-dimensional projection exposure method to the three-dimensional structure surface intermittently sent. It is sectional drawing of the stereographic projection exposure apparatus which concerns on this invention. It is the three-dimensional figure and sectional drawing of the conical opening hole shape reflection type mirror of the inclination angle of 45 degrees of the three-dimensional projection exposure apparatus which concerns on this invention. FIG. 4 is a three-dimensional view and a cross-sectional view of a quadrangular pyramid aperture-hole-shaped reflective mirror having an inclination angle of 45 ° in the three-dimensional projection exposure apparatus according to the present invention. It is the top view of the mask pattern sample arrange | positioned at the stereographic projection exposure apparatus which concerns on this invention, and the cross-sectional schematic diagram at the time of 1x projection exposure. It is a ray path schematic diagram at the time of using the conical opening hole shape reflection type mirror of the inclination angle of 45 degrees of the stereoscopic projection exposure apparatus which concerns on this invention. It is the cross-sectional schematic at the time of the reduction | restoration projection exposure which used the top view of the mask pattern sample arrange | positioned at the stereographic projection exposure apparatus which concerns on invention, and the planoconvex lens together. It is the cross-sectional schematic at the time of the expansion projection exposure which used the top view of the mask pattern sample arrange | positioned at the three-dimensional projection exposure apparatus which concerns on this invention, and a plano-concave lens together. It is the top view of the mask pattern sample arrange | positioned at the stereographic projection exposure apparatus which concerns on this invention, and the cross-sectional schematic diagram at the time of expansion projection exposure. FIG. 4 is a top view of a mask pattern sample arranged in the stereoscopic projection exposure apparatus according to the present invention and a schematic cross-sectional view at the time of reduced projection exposure. It is a cross-sectional arrangement view of the stereoscopic projection exposure method according to the present invention. It is a figure which shows the pattern of the flat type photomask arrange | positioned at the stereographic projection exposure apparatus which concerns on this invention. It is an optical microscope photograph of the fine concavo-convex structure transferred to the brass cylindrical surface coated with Microposit S1830 resist by the stereoscopic projection exposure apparatus according to the present invention.

  First, the principle of the stereoscopic projection exposure method will be described with reference to FIGS. The parallel ultraviolet light output from the ultraviolet light source passes through the plate-shaped photomask. In the photomask of FIG. 2, a concentric pattern is illustrated.

Ultraviolet rays are shielded by the black part of the mask pattern. Ultraviolet light that has passed through the white part is reflected by a mirror having a three-dimensional reflecting surface.
The mirror surface has a mortar shape, and a cylindrical substrate is vertically arranged at the center of the mirror. The surface of the cylindrical substrate is coated with an ultraviolet photosensitive resin, and is exposed to ultraviolet rays reflected by the mirror surface. In the case of a positive type ultraviolet photosensitive resin, as illustrated in FIG. Are exposed in an annular shape having a predetermined width.

The annular colored photosensitive portions colored in gray are continuously continuous in the circumferential direction, and two adjacent photosensitive portions are connected in the axial direction of each cylindrical substrate. Further, as shown in FIG. 3, a through-hole is processed in the center of the photomask and the three-dimensional mirror, and the cylindrical substrate coated with the ultraviolet photosensitive resin is intermittently fed to transfer the entire mask pattern on the photomask. This pattern can be repeated indefinitely as a unit, and the physical restriction of the cylindrical substrate with respect to the feed direction is eliminated, and in principle, a seamless pattern can be transferred unlimitedly by batch processing.
Such transfer is particularly effective when a specific pattern is repeatedly formed continuously in the axial direction of the cylindrical substrate.

  In this way, by developing the resin exposed to ultraviolet rays, a seamless seamless pattern connected to the surface of the cylindrical base material can be transferred without limitation.

Next, an embodiment of the ultraviolet exposure apparatus will be described with reference to FIG.
FIG. 4 is a cross-sectional view of the main part of the optical stereoscopic projection exposure apparatus according to this embodiment.
The light exposure apparatus is composed of an upper stage 5 having a photomask fixing mechanism 6 for fixing a flat photomask 7 and a lower stage 11 for holding a cylindrical three-dimensional structure base material 9 which is a light irradiation object. The lower stage 11 is supported by a pedestal 14.

  A lamp 1 for generating ultraviolet rays is provided at the uppermost part of the upper stage 5, and the ultraviolet rays generated by the lamp 1 are deflected by ultraviolet collimating means 3 including a plano-convex lens 8 and a mirror, and the like. Adjusts the intensity distribution of the ultraviolet rays by the ultraviolet intensity adjusting means 2 comprising a filter or the like.

The adjusted ultraviolet rays are irradiated onto the flat photomask 7, and a mask pattern is projected depending on the presence or absence of an ultraviolet photosensitive material which is an ultraviolet absorber applied to the mask surface.
Note that a gray scale mask capable of adjusting the transmission intensity of ultraviolet rays may be used as the mask.

  The flat photomask 7 is held on the mask fixing stage 5 by a mask fixing mechanism such as a vacuum chuck, and the position of the photomask fixing stage 5 is adjusted by the photomask position adjusting mechanism 4 made of a micrometer or the like. Alignment with the lower stage 11 is possible.

The ultraviolet rays that have passed through the mask are condensed through an optical system such as one lens or a plurality of lenses or mirrors, and are reflected in the shape of a mortar opening hole formed on the inner surface of the lower stage 11. It enters the mirror surface and is reflected.
A three-dimensional structure 9 is held through a fixing mechanism 12 at the center of the lower stage 11, and an ultraviolet photosensitive material 10 is applied to the surface of the three-dimensional structure 9.

The light reflected by the mirror surface is irradiated onto the ultraviolet photosensitive material 10 applied to the surface of the three-dimensional structure 9, and the pattern of the flat photomask 7 is projected three-dimensionally on the surface of the three-dimensional structure base 9. Will be.
The distance between the upper stage 5 and the lower stage 11 can be changed by a gap adjusting mechanism 13 that moves the upper stage 5 up and down, and can be adjusted to an optimum inter-stage distance.

  Further, the lamp 1, the ultraviolet intensity adjusting means 2, the ultraviolet collimating means 3, the photomask position adjusting mechanism 4, the mask fixing stage 5, the photomask fixing mechanism 6, the flat photomask 7 and the plano-convex lens 8 illustrated in FIG. Are provided with through holes so that the three-dimensional structures 9 can be supplied intermittently. The lower stage 11, the fixing mechanism 12, and the pedestal 14 are each provided with a through hole so that the three-dimensional structure 9 after the exposure can be intermittently discharged.

Next, a specific ultraviolet three-dimensional projection exposure will be described with reference to FIGS.
In the example of FIGS. 2 and 3, a mortar opening hole-shaped reflection mirror having a mirror surface with an inclination angle of 45 ° is formed on the inner surface of the lower stage 11, and a three-dimensional view and a sectional view thereof are shown in FIG. It is shown.

  The shape of the opening hole may be determined according to the shape of the exposure object. For example, as illustrated in FIG. 4, when the three-dimensional structure 9 is a cylinder, a conical hole shape is formed on the inner surface of the lower stage 11. When the three-dimensional base material 9 to be irradiated with ultraviolet rays is a quadrangular prism, a three-dimensional reflecting mirror surface having a quadrangular pyramid shape as shown in FIG. 6 is formed. do it.

In the example shown in FIG. 7, the parallel light 19 transmitted through the flat photomask 15 is reflected by the mortar opening hole-shaped reflection mirror 18 having a mirror surface with an inclination angle of 45 ° and applied to the surface of the three-dimensional structure base material 16. The conceptual diagram irradiated on the ultraviolet-sensitive material 17 is shown.
The flat photomask 15 is formed with a plurality of concentric circle patterns so as not to cross each other, and each circle is connected by a connecting portion in the radial direction so that a mortar opening hole shape reflection By the mirror 18, it is transferred onto the surface of the cylindrical ultraviolet photosensitive material 17 as a pattern of a seamless circumferential portion having no seam in the circumferential direction.

In addition, a radial straight line passing through the center point connecting the adjacent circles of the concentric circle pattern on the mask, or an extension line thereof is an axial direction (vertical direction) on the surface of the cylindrical ultraviolet photosensitive material 17, and an axial direction. Is transferred as a linear portion connecting the circumferential portions adjacent to each other.
In addition, not only concentric circles but also a plurality of closed curves such as ellipses that do not intersect with each other may be formed in the flat photomask 15, and two adjacent closed curves may be connected by a straight line portion or a curved portion.

Here, when the mortar opening hole shape reflection type mirror 18 having a mirror surface with an inclination angle of 45 ° is used, the optical path from the reference surface via the reflection points P ₁ and P ₂ in FIG. 8 to the surface of the cylindrical irradiation object The length is
d ₁ + r ₁ = d ₂ + r ₂ = D (1)
The ultraviolet ray reflected at any position of the mortar opening hole shape reflection type mirror surface is irradiated onto the surface of the cylindrical irradiation object with the same optical path length.

Further, the radial direction of the mirror surface is the same size projection exposure because ultraviolet rays are reflected on a straight line with an inclination angle of 45 °, but the circumferential direction of the mirror surface is a reduced projection exposure according to the radius of the circumference. Become. Radially defined unit length, on the circumference of a circle cut mirror cylindrical irradiation object surface at any angle theta, ultraviolet rays reflected by r ₁ theta, P ₂ in the case where ultraviolet rays are reflected by P ₁ In this case, the light on the circumferential mirror surface having a length of r ₂ θ is collected.

At the reflection point P ₀ where the aperture radius of the mortar opening hole-shaped reflective mirror coincides with the radius of the cylindrical irradiated body, the reduction ratio is 1, and theoretically, the projection exposure is the same magnification. For this reason, the ultraviolet rays passing through the reflection points P ₁ and P ₂ are
r ₀ θ / (r ₀ + r ₁ ) θ: r ₀ θ / (r ₀ + r ₂ ) θ = r ₀ / (r ₀ + r ₁ ): r ₀ / (r ₀ + r ₂ ) (2 )
Reduced at the rate indicated by.
From equation (2), it can be seen that the pattern arranged relatively outside in the pattern area of the flat photomask is projected at a higher reduction ratio.

Therefore, when designing a mask pattern, the dimensions must be adjusted in consideration of the reduction rate in the circumferential direction according to the distance from the center of the pattern area.
Furthermore, the difference in the reduction ratio at the reflection point also changes the amount of ultraviolet irradiation. Since the mirror surface with a large radius in the circumferential direction collects a larger amount of light, the pattern arranged outside the flat photomask is exposed with a higher irradiation intensity. In general, an ultraviolet exposure apparatus such as a contact aligner has an optical system designed so that a photomask is irradiated with an equal amount of ultraviolet rays.

In this embodiment, the ultraviolet intensity distribution in the surface is controlled by the ultraviolet intensity adjusting mechanism 2 shown in FIG. 4 so that the ultraviolet ray is irradiated onto the surface of the cylindrical ultraviolet photosensitive material 17 with a uniform intensity. There must be.
That is, the ultraviolet intensity applied to the corresponding circular pattern on the surface of the columnar ultraviolet photosensitive material 17 increases as the circle on the outer peripheral side of the mask pattern increases, so that the transmitted ultraviolet light is reduced by the ultraviolet intensity adjusting mechanism 2. is required.

  Specific methods of adjusting the UV intensity include the method of utilizing the output intensity distribution in the radial direction of the UV lamp as it is, the insertion of a density filter and lens that can adjust the UV transmission intensity, the material of the UV absorbing material of the photomask, Various methods are conceivable, such as a gray scale that changes the thickness, and a coating that changes the reflectivity of the mortar opening hole-shaped reflective mirror surface.

  FIG. 7 shows an example of projection exposure onto a cylindrical surface using a mortar opening hole-shaped reflective mirror 18 having a mirror surface with an inclination angle of 45 °, but by inserting plano-convex lenses before and after the photomask 15, It is possible to transfer the pattern by reducing and projecting the pattern on the surface of the three-dimensional structure in all directions. A plano-convex lens is a lens in which one side is a convex lens and the opposite side is a plane.

In the example shown in FIG. 9, the parallel ultraviolet light that has passed through the mask 20 is collected by the plano-convex lens 21 and is incident on the mortar opening hole-shaped reflective mirror 24.
The light reflected by the mirror 24 is irradiated onto the surface of the three-dimensional structure 22 while condensing. By optimizing the convex lens shape of the plano-convex lens 21 according to the distance from the lens surface to the reflecting mirror 24 and the ultraviolet photosensitive material 23 such as a resist coated on the surface of the three-dimensional structure base 22, It is also possible to form an image on the ultraviolet photosensitive material 23 coated on the surface 22.

On the contrary, as shown in FIG. 10, when a plano-concave lens 27 (a lens having a concave lens on one side and a flat surface on the other side) is inserted, the pattern of the flat photomask 26 is enlarged. Thus, it can be transferred to the surface of the three-dimensional structure substrate 29.
FIG. 10 schematically shows an ultraviolet ray introduction path to the surface of the three-dimensionally structured substrate 29 when the flat plate photomask 26 having the same pattern shape as that of FIG. 7 is used.

  In this way, by using a plano-convex lens and a plano-concave lens in combination, the pattern of the flat photomask is reduced or enlarged and projected onto the surface of the three-dimensional structure, and the photosensitive ultraviolet photosensitive material is developed, thereby developing the three-dimensional structure. A fine concavo-convex structure can be formed on the surface.

In order to adjust optical aberration, in addition to the convex lens and concave lens illustrated in FIGS. 9 and 10, a plurality of optical components such as a biconvex lens, a biconcave lens, and a mirror are combined and projected like a relay lens. The scale of the image may be adjusted at an arbitrary ratio.
Further, by processing the mirror surface of the mortar opening hole-shaped reflective mirror into a convex shape or a concave shape, the pattern can be projected in an enlarged or reduced direction in the vertical direction of the three-dimensional structure.

FIG. 11 is a schematic diagram when the mask pattern illustrated in FIG. 7 is reflected by the convex mortar opening hole-shaped reflective mirror 35 and the enlarged pattern is transferred to the surface of the three-dimensional base material 33.
In this case, the pattern drawn on the flat photomask 32 is enlarged in the axial direction passing through the center of the pattern by the convex mortar opening hole-shaped reflective mirror 35.

  On the other hand, when the concave mortar opening hole shape reflecting mirror 40 as shown in FIG. 12 is used, the pattern on the flat photomask 37 is reduced in the axial direction passing through the pattern center, It is projected onto the ultraviolet photosensitive material 39 formed on the surface. Of course, in this embodiment as well, there is a case where a convex or concave mortar opening hole reflection mirror is used in combination with a plano-convex lens or a plano-concave lens, and the pattern is projected while changing the magnification in the circumferential direction and the vertical direction.

  Next, based on FIG. 13, a specific example in the case of performing ultraviolet three-dimensional projection exposure on the positive ultraviolet photosensitive resin 46 applied to the surface of the cylindrical base material 47 will be described.

The mortar opening hole-shaped reflective mirror 47 needs to ensure high reflectivity as well as durability against ultraviolet irradiation.
Moreover, since the ultraviolet light source used the double-sided mask aligner PEM-800 by Union Optical Co., Ltd., the main wavelengths of output ultraviolet light: λ are 436, 405, and 365 nm.
In order to reflect ultraviolet rays of these wavelengths with a loss of 10% or less, it is calculated that the surface roughness of the mirror reflecting surface is λ / 20, and the mirror was processed with the maximum height: Rmax = 20 nm or less. .

  In this case, the surface roughness of the mirror produced by ultraprecision machining of aluminum was Rmax = 18 nm, and the shape accuracy (straightness) was a peak value: PV = 50 nm. On the exposure stage of the double-sided mask aligner, a mortar opening hole-shaped reflective mirror 47, a brass cylindrical base material 45 to be finally irradiated with ultraviolet rays, a relay lens 44, and a flat plate photomask 43 are shown in FIG. Arranged to be.

  A mortar opening hole-shaped reflective mirror 47 is arranged on the lowermost reference stage, and a cylindrical base material 47 having a diameter of 5 mm coated with an ultraviolet photosensitive resin 46 is vertically fixed at the center and fixed directly above. In addition, a total of four relay lenses 44 are arranged to correct chromatic aberration and Seidel aberration. From the simulation results, it was confirmed that the pattern having a line width of 100 μm can project the shape relatively accurately.

Above the relay lens 44, a flat photomask 43 having a 5-inch angle is arranged.
The ultraviolet transmissive portion of the photomask 43 is made of quartz, and the light shielding portion is formed of a Cr layer. The positions of the relay lens 44 and the flat plate photomask 43 can be finely adjusted in three axial directions. .

The pattern of the flat photomask 43 will be described with reference to FIG.
The pattern of the flat photomask 43 is based on a concentric pattern, and a circular pattern, a round dot pattern, and a spiral pattern are arranged in a range of 20 mm in diameter. The size of the pattern is a minimum of 50 μm and a maximum of 100 μm. The cross pattern at the center is an alignment mark for adjusting the exposure position.

Next, the procedure of an ultraviolet exposure experiment when using the above-described flat photomask 43 will be described.
(1) The surface of a brass cylindrical base material 47 having a diameter of 5 mm was polished with a diamond bit and diamond mixed abrasive grains, and the surface roughness was 10 μm or less.
(2) While rotating the brass cylindrical base material 45 at a high speed, an ultraviolet photosensitive resin MICROPOSIT S1830 manufactured by Shipley, whose concentration was adjusted with a thinning solution, was applied by a spray coating method.
(3) The brass cylindrical base material 47 was heated at 150 ° C. for 20 minutes with a hot plate to evaporate the solvent of the ultraviolet photosensitive resin applied to the surface, and the ultraviolet photosensitive resin layer 46 was formed in the entire circumferential direction. .
(4) After taking a sufficient time to cool to room temperature, a brass cylindrical base material 45 was placed vertically in the center of the mortar opening hole-shaped reflective mirror 47.
(5) A mortar opening hole-shaped reflective mirror 47, a relay lens 44, and a flat plate photomask 43 were arranged on an exposure stage of a double-sided mask aligner, and their positions were adjusted.
(6) After irradiating with ultraviolet rays for 10 to 30 seconds, development was performed by immersing in a special developer MICROPOSIT MF-319 for 2 to 3 minutes. By this step, the ultraviolet photosensitive resin in the portion irradiated with ultraviolet rays is removed, and the portion shielded from ultraviolet rays remains as a resin structure.

  When the pattern obtained by such a process was observed with an optical microscope, a round dot pattern with a diameter of 50, 75, and 100 μm and a spiral pattern with a line width of 50 and 100 μm were transferred to the brass cylinder surface.

The obtained resist pattern after development was observed with an optical microscope, and the results are shown in FIG. It was confirmed that the mask pattern on the flat plate was clearly transferred to the surface of the cylindrical base material through the mortar opening hole shape reflection type mirror, and the edge portion of the fine concavo-convex structure was also clear. It was also confirmed that the round dot pattern, which was a perfect circle on the flat photomask, was transferred as an ellipse by reduction projection in the circumferential direction.
A perfect circle dot pattern having a diameter of 100 μm is transferred as an ellipse having a minor diameter of 58 μm and a diameter of 100 μm. As shown in FIG. 14, on the flat photomask, a round dot pattern having a diameter of 100 μm is arranged on the circumference having a radius of 4.35 mm from the center. Further, since the radius of the cylindrical irradiation object with a reduction ratio of 1 is 2.50 mm, the reduction ratio is 2.50 / 4.35≈0.57, and the pattern with a line width of 100 μm is 0.57 × The projection is reduced to a line width of 100 μm = 57 μm. This value coincides with the value of the short diameter of the oval transfer pattern illustrated in FIG.

The optical stereoexposure method according to the present invention includes, for example, an actuator such as a catheter in which the shape of the device itself is preferably cylindrical on the premise of insertion into a blood vessel, a semiconductor element or an optical element on a linear substrate In the development of an on-fiber device that gives this function, it is extremely useful as a technique for forming a three-dimensional surface wiring or a flow path pattern.
Also, in the production of a cylindrical mold in roll-to-roll imprinting, a wide range of processes for processing a seamless fine concavo-convex structure without a seam when the cylindrical mold rotates once in the circumferential direction can be widely handled.

1: UV irradiation lamp 2: UV intensity adjusting means 3: UV collimating means 4: Photomask position adjusting mechanism 5: Photomask fixing stage 6: Photomask fixing function,
7, 15, 20, 26, 32, 37, 43: Flat type photomask 8, 21: Plano-convex lens 9, 16, 22, 27, 33, 38: Three-dimensional structure base material 10, 17, 23, 29, 34, 39, 46: UV photosensitive material 11, 47: Mortar opening hole shape reflection type mirror 12: Three-dimensional base material fixing mechanism 13: Gap adjusting mechanism 14: Pedestal 18, 24, 30: Mortar opening hole shape with an inclination angle of 45 ° Reflective mirror 19: Light beam 22: Plano-convex lenses 25, 31, 41: Light beam 28: Plano-concave lens 35: Convex mortar opening hole-shaped reflection mirror 36: Light beam 40: Recessed mortar opening hole-shaped reflection mirror 42: Ultraviolet light 44: Relay lens 45: Brass cylindrical base material

Claims (7)

  On the mask surface, light is irradiated onto a flat plate photomask surface having a predetermined pattern, and the transmitted light is reflected by a three-dimensional reflection type mirror having a mortar-shaped opening hole and applied to the surface of the three-dimensional structure. By irradiating the photosensitive material and intermittently supplying the three-dimensional structure, the pattern on the mask surface is seamless on the surface of the three-dimensional structure, and the pattern is continuous in the axial direction. As a light projection exposure apparatus that can be transferred indefinitely. The light projection exposure apparatus according to claim 1,
The flat plate photomask is a light projection exposure apparatus having a pattern in which a plurality of closed curves that do not intersect with each other and a connecting portion that connects two adjacent closed curves are combined. The light projection exposure apparatus according to claim 1 or 2,
The flat type photomask is composed of a light transmitting part and a light shielding part, and is a light projection exposure apparatus that can be aligned with a three-dimensional structure coated with a photosensitive material. The light projection exposure apparatus according to claim 1, wherein
The light radiated on the flat photomask surface is emitted from a light generator and then collimated, focused, or diffused by lenses arranged before and after the flat photomask. Projection exposure apparatus.   5. The light projection exposure apparatus according to claim 1, wherein the three-dimensional reflection type mirror processes a mortar-shaped opening hole using a metal or glass material as a base material, and an inner peripheral wall section has a straight or curved surface shape. A light projection exposure apparatus in which the inner peripheral wall is coated with a material that reflects the light. The light projection exposure apparatus according to claim 1,
The three-dimensional reflection type mirror reflects the light transmitted through the flat plate photomask as one of parallel light, focused light, and divergent light according to the cross-sectional shape of its inner peripheral wall, and the pattern on the mask surface is the same size. Alternatively, a light projection exposure apparatus in which the photosensitive material applied on the surface of the three-dimensional structure is exposed by being reduced or enlarged. Positioning a flat photomask having a predetermined pattern on the mask surface;
Positioning a three-dimensional structure in which a photosensitive material is applied on the surface inside a three-dimensional reflection type mirror having a mortar-shaped opening hole;
Irradiating light on the surface of the flat photomask;
Reflecting the transmitted light by the three-dimensional reflection type mirror and exposing the photosensitive material applied to the surface of the three-dimensional structure;
The positioning three-dimensional structure consists of a supply step intermittently,
A light projection exposure method in which a pattern on the mask surface is transferred indefinitely as a seamless pattern and a continuous pattern in the axial direction.