Exposure equipment

Abstract

To provide an exposure apparatus capable of performing one-shot exposure on a surface of an exposure object having a step.SOLUTION: An exposure apparatus 100 exposes an outer surface of an exposure object M by using speckle light. The exposure apparatus includes: a light source 10 that emits coherent light; a light diffusion member 20 disposed on an optical axis AX of the light source 10; a collimate lens 30 that changes speckle light being diffused by the light diffusion member 20 into parallel light; a collimate lens holding table 40 capable of moving the collimate lens 30 in a direction of the optical axis AX; and an exposure object holding table 50 that holds the exposure object.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an exposure apparatus.

Background Art

[0002] In recent years, it has been known that by processing irregular structures of micrometers to sub-micrometers on the surface of a material, functions not possessed by the material can be imparted. The function varies greatly depending on the size and density of the structures formed on the surface, and there are a wide range of applications.

[0003] Examples of functions that can be imparted include imparting water repellency or hydrophilicity (for example, the improvement effect of dispensing residue by processing the tip of a pipette chip, and the use in dispensing devices, medical devices, and analytical devices), imparting high lubricity (for example, imparting the effect of reducing wear and friction of a sliding part. By performing microfabrication (dimples) on a metal surface and storing oil therein, the effect of reducing wear and friction of the sliding part can be obtained), imparting the effect of reducing frictional force (for example, improving slidability by controlling frictional force due to a reduction in contact area. Improving the combustion energy of an engine in the automotive industry and improving the life of parts by suppressing deterioration), etc. [[ID=1这是一段关于曝光装置的专利文本,主要介绍了相关技术领域和背景技术。

[0004] In the method of fabricating fine structures on a metal surface, machining is used in the case of the micrometer order, and in the case of the sub-micrometer order, direct processing methods using energy beams (ion beams, femtosecond lasers (ultrashort pulse lasers), high-power lasers such as thermal lithography), methods using electron beams or synchrotron light are known, and precise structures can be formed. As another method of microfabrication, there is photolithography technology. Photolithography technology uses a mask pattern that is the original drawing of a pattern, irradiates light from above the mask, and projects and reduces the mask pattern through a projection lens. Therefore, it is a processing method excellent in pattern reduction and is a processing technology suitable for precisely fabricating a plurality of the same mask patterns. The resolution R in exposure using a reduction projection lens is given by equation (1), and depends on the wavelength λ of the light source and the numerical aperture NA(sinθ: in air). Here, k1 is the process factor. From equation (1), it can be seen that the shorter the wavelength and the larger the numerical aperture, the higher the resolution and the finer the pattern that can be transferred. The depth of focus DOF ​​is given by equation (2), where k2 is the process factor. From equations (1) and (2), it can be seen that increasing NA(sinθ) to reduce the resolution and create a finer pattern reduces the depth of focus by the square of the value. In other words, the finer the pattern obtained, the smaller the depth of focus becomes.

[0005]

number

[0006] One known microfabrication technique for irregular patterns is photolithography using speckle light (for example, Patent Document 1). This technique generates speckle light by shining light on a light-diffusing member and projects the speckle light onto an object coated with photosensitive resin, thereby transferring fine patterns of random shapes without the need for a mask. For this reason, it is attracting attention as a technique that can transfer micrometer-order fine patterns without using a master plate with a predetermined pattern and without a projection lens. Speckle light utilizes the irregular arrangement and irregular shape of light intensity distribution caused by the interference and diffraction phenomena of light, and by shining speckle light onto a surface coated with photosensitive resin, it is possible to create micrometer-order fine photosensitive resin patterns. By using this as a masking material and etching metal, fine structures can be created on the metal surface. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2005-140967 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, methods using energy beams are problematic because the lasers themselves are expensive, and they cannot handle a wide variety of shapes, including three-dimensional surfaces with steps and other irregularities. Therefore, they are not readily usable for product prototyping, and their applications are limited. Currently, there is no simple and inexpensive microfabrication method that can be used for three-dimensional surfaces. Furthermore, in this photolithography technology, as the pattern becomes smaller, increasing the reduction projection magnification narrows the exposure area. Also, because a projection lens is used, the depth of field becomes shallower depending on the size of the pattern being transferred according to equation (2) above, making it impossible to create a fine pattern in a single exposure on an object with steps. For this reason, photolithography technology is generally only used on highly flat surfaces such as silicon wafers, and it is not possible to expose a fine pattern on a surface with large steps in a single process.

[0009] Speckle lithography technology is designed for flat surfaces. Therefore, it is not possible to transfer a pattern to a three-dimensional surface with steps ranging from a few millimeters to tens of centimeters in a single pass. This is because the light intensity distribution of speckle light depends on the distance from the master light-diffusing material to the object being exposed. In other words, as shown in Figure 6, the light intensity distribution of speckle light weakens with the square of the distance between the light-diffusing material and the object being exposed, so objects with large steps cannot be exposed under the same exposure conditions. Furthermore, because the pattern distribution of speckle light widens in proportion to the distance, the density of the transferred fine pattern changes.

[0010] This invention has been made in view of the above circumstances, and aims to provide an exposure apparatus capable of exposing the surface of an object to be exposed, which has steps, in a single step. [Means for solving the problem]

[0011] To solve the above problems, the present invention provides the following means.

[0012] One aspect of the present invention is an exposure apparatus for exposing the outer surface of an object to be exposed using speckle light, comprising: a light source that emits coherent light; a light diffusing member positioned on the optical axis of the light source; a collimating lens that converts the speckle light scattered by the light diffusing member into parallel light; a collimating lens holder that can move the collimating lens in the optical axis direction; and an object holder that holds the object to be exposed.

[0013] A second aspect of the present invention is an exposure apparatus according to the first aspect, wherein the collimating lens is detachable from and replaceable from the collimating lens holder.

[0014] A third aspect of the present invention is an exposure apparatus according to aspect 1 or aspect 2, wherein the light diffusing member is detachable and replaceable.

[0015] Aspect 4 of the present invention is an exposure apparatus in any one of aspects 1 to 3, wherein a density filter is provided before or after the collimating lens on the optical axis.

[0016] Aspect 5 of the present invention is an exposure apparatus in any one of aspects 1 to 4, wherein a homogenization optical system is provided between the collimating lens and the light diffusing member.

[0017] Aspect 6 of the present invention is an exposure apparatus in any one of aspects 1 to 5, wherein a beam expander is provided between the light source and the light diffusing member.

[0018] Aspect 7 of the present invention is an exposure apparatus in any one of aspects 1 to 6, wherein a reduction projection optical system is provided between the light diffusing member and the collimating lens, and the collimating lens is positioned such that its focal point is at approximately the imaging position of the reduction projection optical system. [Effects of the Invention]

[0019] According to the exposure apparatus of the present invention, an exposure apparatus capable of collectively exposing the surface of an object to be exposed having steps can be provided.

Brief Description of the Drawings

[0020] [Figure 1] It is a conceptual diagram of an exposure apparatus according to the present invention. [Figure 2] It is a schematic cross-sectional view showing the schematic configuration of an exposure apparatus according to the first embodiment. [Figure 3] It is a conceptual diagram of an exposure apparatus according to the second embodiment. [Figure 4] It is a flowchart showing the procedure of step exposure. [Figure 5] Assuming steps of 50 mm, 100 mm, 150 mm, and 200 mm in the depth direction of the optical axis with respect to the reference plane (0 mm), the distance between the collimating lens and the silicon wafer was changed, exposed for the same exposure time, and the results observed with an optical microscope after development are shown. [Figure 6] It is a conceptual diagram for explaining that the light intensity distribution of speckle light weakens as the distance squared and the pattern arrangement widens in proportion to the distance, resulting in a change in density.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, the present invention will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show enlarged portions that are characteristic for the sake of clarity, and the dimensional ratios of each component may be different from the actual ones. The dimensions and the like exemplified in the following description are merely examples, and the present invention is not limited thereto, and can be appropriately modified and implemented within the scope where the effects of the present invention are achieved. Hereinafter, even if not particularly described, the configuration described in one embodiment may be applied to other embodiments.

[0022] FIG. 1 shows a conceptual diagram of an exposure apparatus according to the present invention. The exposure apparatus 100 shown in Figure 1 is an exposure apparatus capable of exposing the surface Ma of an object to be exposed having a step D using speckle light S, and comprises a light source 10 that emits coherent light, a light diffusing member 20 positioned on the optical axis AX of the light source 10, and a collimating lens 30 that converts the speckle light scattered by the light diffusing member 20 into substantially parallel light.

[0023] The exposure apparatus according to the present invention is a lithography technique that applies speckle light to the surface of a photosensitive material to transfer a pattern with an irregular arrangement and irregular shape. This exposure apparatus is capable of transferring a fine pattern of several micrometers in size to a three-dimensional object to be exposed that has a large step in the depth direction exceeding 20 cm in a single exposure. There is a strong need for fine processing not only on flat surfaces but also on three-dimensional surfaces with steps, but energy beam methods and photolithography techniques cannot handle the wide variety of shapes with steps other than flat surfaces. Furthermore, even if photolithography techniques using speckle light are used, the speckle light spread by the light diffusing member weakens with the square of the distance, so it is not possible to expose objects with large steps under the same exposure conditions. In addition, the pattern arrangement widens in proportion to the distance, so the pattern density changes. For this reason, it is not possible to transfer a fine pattern of several micrometers in size to an object to be exposed that is not flat in a single exposure.

[0024] (First Embodiment) Figure 2 is a schematic cross-sectional view showing the general configuration of the exposure apparatus according to the first embodiment. The exposure apparatus 100 shown in Figure 2 is an exposure apparatus capable of exposing the surface Ma of an object to be exposed having a step D using speckle light S, and comprises a light source 10 that emits coherent light, a light diffusing member 20 positioned on the optical axis AX of the light source 10, a collimating lens 30 that converts the speckle light scattered by the light diffusing member 20 into parallel light, a collimating lens holder 40 that can move the collimating lens 30 in the direction of the optical axis AX, and an object to be exposed holder 50 that holds the object to be exposed. The exposure apparatus 100 can simultaneously expose the surface Ma of the object to be exposed M, which has a step D. The step D is, for example, 1 mm to several hundred mm.

[0025] The exposure apparatus 100 shown in Figure 2 further includes an illumination optical system 11 that controls the illumination area placed between the light source 10 and the light diffusion member 20, a light diffusion member support section 60 that supports the light diffusion member 20, a light source support section 70 that supports the light source 10 via a fixed base 2 on which the light source 10 is placed, and a mounting base 1 on which the entire exposure apparatus is placed.

[0026] <Exposed object> The object to be exposed M by the exposure apparatus according to this embodiment is, for example, a three-dimensional object having a step D, but three-dimensional objects without a step D can also be exposed. Furthermore, the object can be a three-dimensional object whose cross-section is circular, elliptical, or has a curved outer perimeter, or a three-dimensional object with a polygon such as a quadrilateral.

[0027] Examples of objects to be exposed M include not only silicon wafers with high flatness, but also three-dimensional metal structures such as stainless steel and brass. During exposure, the object to be exposed M is exposed with a photosensitive material (resist) applied to its surface Ma to a predetermined thickness (for example, 1 μm to several hundred μm). The object to be exposed, M, is held in a detachable state by a holding mechanism such as a suction jig, which is not shown in the figure.

[0028] <Light source, illumination optical system> Examples of light sources that emit coherent light include lasers and LDs (laser diodes). The light from the light source can be guided to the exposure apparatus via a fiber and connected with an FC connector. Because the connection and disconnection can be reproducibly performed by using FC connectors, changing the wavelength of the light source only requires replacing the light source with another one, eliminating the need for a large-scale optical system.

[0029] In the exposure apparatus 100 shown in Figure 2, there is an illumination optical system 11 that controls the illumination area between the light source 10 and the light diffusion member 20, but it is also possible to configure it so that coherent light emitted from the light source 10 is directly irradiated onto the light diffusion member 20. The light rays emitted from the light source 10 are magnified and reduced by the illumination optical system 11 (11a, 11b, and 11c in the example shown in Figure 2) to illuminate the light diffusion member 20 at a predetermined size. In illumination optics that control the illumination area, it is preferable to include a beam expander for expanding the illumination area.

[0030] <Light Diffusing Material> By shining coherent light onto a light-diffusing material, it is possible to generate speckle light, which is scattered light arranged randomly, resulting in a random shape of light intensity. By positioning a collimating lens system so that the light-diffusing material is approximately at the focal point of the spread speckle light, the light rays become parallel, and a speckle light intensity distribution pattern can be transferred to the surface of an object to be exposed, even if it has large steps, in one go.

[0031] The light-diffusing member 20 shown in Figure 2 is of the transmissive type, but it may also be of the reflective type. In the case of a transmissive light diffusing member, a diffuser plate made of flat glass with one or both sides processed to be roughened may be used. Alternatively, in the case of a transmissive light diffusing member, opal glass in which light is diffused within the material may be used. In the case of reflective light-diffusing members, a diffuser plate with a roughened surface is also acceptable. Furthermore, in the case of reflective light-diffusing members, a complete diffusing material such as Spectralon may be coated on the surface.

[0032] The light diffusing member 20 may be detachable from the light diffusing member support 60.

[0033] <Collimating Lenses> A collimating lens is a lens that has been aberrated to obtain parallel light, and any known collimating lens can be used as the collimating lens 30. The collimating lens 30 may consist of one lens or multiple lenses (in this case, it may be referred to as a collimating optical system or collimating lens system in this specification). The collimating lens can be either a fixed-focus or variable-focus lens. With a variable-focus collimating lens, it is possible to form fine patterns by shortening the focal length, while conversely, it is possible to form larger patterns by lengthening the focal length.

[0034] Even when using a fixed-focus collimating lens, it is possible to form fine patterns by using a collimating lens with a short focal length. On the other hand, it is possible to form larger patterns by using a collimating lens with a longer focal length. By selecting the focal length of the collimating lens, the shape of the pattern transferred to the exposed object can be controlled.

[0035] The collimating lens 30 is held by a collimating lens holder 50 that is movable in the optical axis direction.

[0036] The collimating lens 30 may be detachable and replaceable from the collimating lens holder 50. By replacing it with a collimating lens with a different focal length, the size of the pattern to be transferred can be changed.

[0037] The collimating lens 30 is made detachable, and the lens diameter is selected to match the light scattering characteristics of the diffusing material, so that almost the entire light scattering angle can be obtained. This reduces light loss and allows for exposure over a wide area.

[0038] By configuring at least one of the light diffusing member 20 and the collimating lens 30 to be movable in the optical axis AX direction, the distance between the light diffusing member 20 and the collimating lens 30 can be adjusted. This allows control over the shape of the pattern transferred to the object being exposed.

[0039] <Exposed object holding section> The object to be exposed M is held by the object to be exposed holder. Preferably, the object to be exposed holder is equipped with a separate or integrated moving mechanism (object to be exposed moving mechanism) for moving the position and orientation of the object to be exposed. The object to be exposed movement mechanism has a movement mechanism that can translate in the direction of the optical axis (light ray), so even in a configuration where the rotational axis symmetric reflective mirror does not move, the object to be exposed M can be moved to a predetermined position on the inner surface side of the rotational axis symmetric reflective mirror.

[0040] The object to be exposed holding unit 40 shown in Figure 2 is mounted on a mounting table 1. The object to be exposed holding unit 40 includes a gripping unit 40a for gripping the object to be exposed M, a z-axis rotation stage 40b on which the gripping unit 40a is mounted and fixed, and which is rotatable about the z axis, a z-axis translational movement stage 40c on which the z-axis rotation stage 40b is mounted, and which is translatably movable in the z direction (direction perpendicular to the xy plane), a y-axis rotation stage 40d on which the z-axis translational movement stage 40c is mounted, and which is rotatable about the y axis, and an x-axis translational movement stage 40e on which the y-axis rotation stage 40d is mounted, and which is translatably movable in the x-axis (optical axis) direction. The object to be exposed holding unit 40 may further include a y-axis translational movement stage that can translate in the y direction (in a direction perpendicular to the x direction in the horizontal plane) and an x-axis rotational stage that can rotate with respect to the x axis.

[0041] <Collimating lens holder> The collimating lens holder supports the collimating lens from below. The collimating lens holder is equipped with a movement mechanism (collimating lens movement mechanism) that moves the position and orientation of the collimating lens. The collimating lens movement mechanism has a movement mechanism that can translate in the direction of the optical axis (light ray), so even when the object to be exposed M does not move, the object to be exposed M can be moved relative to a predetermined position on the collimating lens movement mechanism.

[0042] The collimating lens holder 50 shown in Figure 2 is mounted on the mounting base 1. The collimating lens 30 is supported by the collimating lens holder 50 mounted on the mounting base 1. The collimating lens holder 50 includes a support portion 50a that directly supports the collimating lens 30, a z-axis translation stage 50b on which the support portion 50a is mounted and which can move translationally in the z-axis direction, a y-axis rotation stage 50c on which the z-axis translation stage 50b is mounted and which can rotate around the y-axis, and an x-axis translation movement stage 50d on which the y-axis rotation stage 50c is mounted and which can move translationally in the x-axis (optical axis) direction. The collimating lens holder 50 may further include a y-axis translation stage that can translate in the y direction (in the horizontal plane, in a direction perpendicular to the x direction), an x-axis rotation stage that can rotate around the x axis, and a z-axis rotation stage that can rotate around the z axis.

[0043] In the exposure apparatus 100 shown in Figure 2, the collimating lens holder 50 has an x-axis translational movement stage 50d. Therefore, without moving the object to be exposed M, the collimating lens 30 can be translated in the direction of the optical axis, allowing the object to be exposed M to be moved relative to the collimating lens 30 to a predetermined position. Furthermore, in the exposure apparatus 100 shown in Figure 2, since the object to be exposed holding unit 40 has an x-axis translational movement stage 40e, the object to be exposed M can be moved to a predetermined position relative to the collimating lens 30 by translating the object to be exposed in the optical axis direction without moving the collimating lens 30. Furthermore, in the exposure apparatus 100 shown in Figure 2, both the x-axis translational movement stage 40e of the object to be exposed holding unit 40 and the x-axis translational movement stage 50d of the collimating lens holding base 50 are used to relatively translate both the object to be exposed M and the collimating lens 30 in the direction of the optical axis, thereby moving the object to be exposed M to a predetermined position on the collimating lens 30.

[0044] <Positioning of the object to be exposed> The object to be exposed, M, attached to a suction jig (not shown), is positioned so that it is approximately within the range of the exposure light. Furthermore, the exposed surfaces Ma1, Ma2, and Ma3 are positioned so that they are perpendicular to the optical axis AX. If positioning is difficult, this can be resolved by changing the exposure light source to a non-photosensitive wavelength of the resist and illuminating the diffusing material. The speckle light emitted from the diffusing material illuminates a certain circular area using a collimating optical system. The stage (object holder) placed on the object to be exposed is adjusted so that it aligns with this light.

[0045] Another method involves first positioning using a different object to be exposed, and then changing to the object to be exposed M and exposing it.

[0046] Once the object to be exposed M is positioned, it is exposed for a predetermined time using an exposure light source with the photosensitive wavelength of the resist. After exposure, the object to be exposed M is developed to form a resist pattern. If a positive-type resist is used, the resist is removed where the light hits it, and if a negative-type resist is used, the areas where the light hits it remain as structures.

[0047] <Light Diffusion Member Support Section> The light-diffusing member support section supports the light-diffusing member from below. The light-diffusing member support section preferably includes a separate or integrated moving mechanism (light-diffusing member moving mechanism) for moving the position and orientation of the light-diffusing member.

[0048] The light-diffusing member support unit 60 shown in Figure 2 is mounted on a mounting base 1. The light-diffusing member 20 is supported by the light-diffusing member support unit 60 mounted on the mounting base 1. The light-diffusing member support unit 60 includes a support unit 60a that directly supports the light-diffusing member 20, a z-axis translation stage 60b on which the support unit 50a is mounted and which can move translationally in the z-axis direction, a y-axis rotation stage 60c on which the z-axis translation stage 60b is mounted and which can rotate around the y-axis, and an x-axis translation movement stage 60d on which the y-axis rotation stage 60c is mounted and which can move translationally in the x-axis (optical axis) direction.

[0049] <Light source support part> The light source support unit supports the light source from below. The light source support section preferably includes a separate or integrated mechanism for moving the position and orientation of the light source (light source movement mechanism).

[0050] The light source support unit 70 shown in Figure 2 is mounted on a mounting base 1. The light source 10 is supported by the light source support unit 70 mounted on the mounting base 1 via a fixed base 2. The light source support unit 70 includes a z-axis rotation stage 70a that can rotate around the z axis, a z-axis translational movement stage 70b on which the z-axis rotation stage 70a is mounted and which can translate in the z direction (direction perpendicular to the xy plane), a y-axis rotation stage 70c on which the z-axis translational movement stage 70b is mounted and which can rotate around the y axis, and an x-axis translational movement stage 70d on which the rotation stage y-axis rotation stage 70c is mounted and which can translate in the x-axis (optical axis) direction. The light source support unit 70 may further include a y-axis translational movement stage that can translate in the y direction (in a direction perpendicular to the x direction in the horizontal plane) and an x-axis rotational stage that can rotate around the x axis.

[0051] <Principles of pattern formation> The size, shape, and density of the resist pattern produced using the exposure apparatus according to the first embodiment vary depending on the exposure wavelength, the laser illumination area, the focal length of the collimating lens, the surface roughness of the diffusing material, and the exposure time. The relationship equation (3) is shown below. To produce a small resist pattern, the exposure wavelength should be short, the illumination area large, the focal length of the collimating lens short, the surface roughness of the diffusing material coarse (increased scattering), and the exposure time short. When a positive-type resist is used, a small hole pattern will be formed in the resist. When a negative-type resist is used, a needle-like pattern will be formed. In the following equation, R is the size of the pattern transferred to the resist, λ is the wavelength of the laser light, D is the irradiation diameter of the laser light, S is the roughness of the light diffusing material, f is the focal length of the collimating lens, and t is the exposure time.

[0052]

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[0053] Next, regarding resist pattern density, if you want to increase the density of the resist pattern, shorten the exposure wavelength, enlarge the illumination area, shorten the focal length of the collimating lens, make the surface roughness of the diffusing material rough (increase scattering), and lengthen the exposure time. In equation (4) below, W is the resist pattern density, λ is the wavelength of the laser light, D is the irradiation diameter of the laser light, S is the roughness of the light diffusing material, f is the focal length of the collimating lens, and t is the exposure time.

[0054]

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[0055] <Tensile Filter> To make the light intensity uniform before and after the collimating lens 30, a density filter 80 may be provided. Speckle light generated after passing through the light diffusing member has an intensity distribution that can be approximated by a Gaussian distribution, in addition to the light intensity distribution that occurs partially in space due to the interference and diffraction phenomena of light, where the light intensity is stronger in the center and decreases towards the periphery. As a result, the exposed pattern is strongly exposed in the center and weakly exposed at the periphery. This causes non-uniformity in the resist pattern, resulting in situations where only parts can be exposed or the transferred resist pattern is uneven. To uniformize this overall light intensity distribution, a density filter is installed according to the light intensity distribution. The density filter is, for example, a grayscale gradient mask or a photomask with gradually changing density, where the density is changed according to the arrangement ratio of dots, and the filter is darker in the center to control strong light in accordance with weak light. This eliminates the non-uniformity of scattered light intensity and makes it possible to expose a uniform pattern over a wide area.

[0056] <Uniformization optical system> A homogenizing optical system (such as a fly-eye lens or beam homogenizer) may be provided between the collimating lens 30 and the light diffusing member. As mentioned above, the speckle light generated after passing through the light diffusing member has an intensity distribution that can be approximated by a Gaussian distribution, where the intensity is stronger in the center and decreases towards the periphery, in addition to the light intensity distribution that occurs partially in space due to the interference and diffraction phenomena of light. For this reason, the exposed pattern is strongly exposed in the center and weakly exposed at the periphery. This causes non-uniformity in the resist pattern, resulting in situations where only a portion can be exposed or the transferred resist pattern is uneven. To homogenize this overall light intensity distribution, an illumination homogenizing optical system such as a fly-eye lens, rod lens, or Kohler illumination is installed. This eliminates the non-uniformity of the scattered light intensity and makes it possible to expose a uniform pattern over a wide area.

[0057] The resist can be uniformly applied to the surface of the object to be exposed by known methods such as spin coating, which creates a uniform film by dropping a photosensitive material and rotating it; spray coating, which involves spraying the material; and dip coating, which involves dipping the object in a photosensitive material and then removing it. By changing the application conditions, the thickness of the resist film applied to the surface of the object to be exposed can be arbitrarily adjusted from 1 μm to several hundred μm.

[0058] (Second Embodiment) Figure 3 shows a conceptual diagram of the exposure apparatus according to the second embodiment. The exposure apparatus 200 shown in Figure 3 is an exposure apparatus capable of exposing the surface Ma of an object to be exposed having a step D using speckle light S, and comprises a light source 10 that emits coherent light, a light diffusing member 20 positioned on the optical axis AX of the light source 10, a collimating lens 30 that converts the speckle light scattered by the light diffusing member 20 into parallel light, and a reduction projection optical system 90 positioned between the light diffusing member 20 and the collimating lens 30.

[0059] <Reduction projection optical system> For example, a microscope objective lens could be used as the reduction projection optical system 90. By positioning the collimating lens so as to approximately coincide with the focal position of the reduction projection lens, a fine pattern with a size multiplied by the reduction magnification can be projected onto a stepped three-dimensional structure.

[0060] <Principles of pattern formation> The size, shape, and density of the resist pattern produced using the exposure apparatus according to the second embodiment vary depending on the exposure wavelength, the laser illumination area, the focal length of the collimating lens, the reduction ratio, the surface roughness of the diffusing material, and the exposure time. The relationship is shown in equation (5) below. To produce a small resist pattern, the exposure wavelength should be short, the reduction ratio should be large, the illumination area should be large, the focal length of the collimating lens should be short, the surface roughness of the diffusing material should be coarse (increased scattering), and the exposure time should be short. In equation (5) below, R is the size of the pattern transferred to the resist, λ is the wavelength of the laser light, D is the irradiation diameter of the laser light, S is the roughness of the light diffusing material, f is the focal length of the collimating lens, and t is the exposure time.

[0061]

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[0062] Next, regarding the resist pattern density, if you want to increase the density of the resist pattern, shorten the exposure wavelength, widen the illumination area, shorten the focal length of the collimating lens, make the surface roughness of the diffusing material rough (increase scattering), and lengthen the exposure time; in the following equation (6), W is the resist pattern density, λ is the wavelength of the laser light, D is the irradiation diameter of the laser light, S is the roughness of the light diffusing material, f is the focal length of the collimating lens, and t is the exposure time.

[0063]

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[0064] (Exposure method) Using the exposure apparatus according to the present invention, the following steps are performed, namely, • The process of shining light from a light source onto a light-diffusing member, • A process of aligning the scattered light using a collimating lens, after the light has been scattered by a light diffusing member. The process of placing an object to be exposed, coated with a photosensitive substance, at a predetermined position on the optical axis, • A process of exposing the object to be exposed by irradiating it with scattered light for a predetermined time, The object to be exposed can be exposed by performing this procedure.

[0065] (Exposure procedure) Using the flowchart in Figure 5, we will explain the procedure for step exposure as an example of an exposure method. First, as a preparation step, in step S1, a photosensitive material is attached to the object to be exposed. The photosensitive material is called a resist, and it is a resin that reacts when exposed to light in a specific wavelength range. For example, if a negative-type resist such as SU-8 is used, only the areas exposed to light will be exposed, and the resist pattern in the areas exposed to light will remain as needles after development. If a positive-type resist such as THMR-iP3300 is used, only the areas exposed to light will be exposed, and the resist pattern in the areas exposed to light will be removed after development to obtain a hole pattern. The photosensitive material can be uniformly attached to the surface of the object to be exposed by methods such as spin coating, which creates a uniform film by dripping the photosensitive material and rotating it; spray coating, which involves spraying the material; and dip coating, which involves dipping the object in the photosensitive material and then removing it. The thickness of the film can be arbitrarily adjusted from 1 μm to several hundred μm.

[0066] In step S2, an object with a shape similar to the object to be exposed is placed in the exposure apparatus beforehand, and the positional relationship between the object to be exposed, the collimating lens, etc., is adjusted.

[0067] In step S3, the object to be exposed is attached to a chuck (not shown) for securing the object to be exposed. In step S4, the desired light-diffusing member is installed. In step S5, the light source is turned on and the light diffusing member is irradiated with light for a predetermined time, and exposure of the object to be exposed is started.

[0068] In step S6, exposure is continued until a predetermined exposure level is reached. In step S7, once the predetermined exposure level is reached, the power to the light source is turned off. In step S8, a decision is made on whether to expose other parts of the object to be exposed. In step S9, if other areas are to be exposed, the object to be exposed is moved in the axial direction and / or rotational direction relative to its axis using the movement mechanism provided in the object holder that holds the object to be exposed, while the object to be exposed is still attached, and exposure to the other areas is started. When there are no more areas to be exposed, exposure is stopped.

[0069] In step S10, the object to be exposed is attached and removed and then subjected to a developing process. The developing process forms a predetermined pattern of photosensitive material. In step S11, etching or plating is performed as needed. The photosensitive material pattern can be used as a masking material for etching, allowing the predetermined pattern to be removed from the object to be exposed. In addition, by applying plating, the plating does not directly adhere to the areas covered by the photosensitive material pattern, allowing for the creation of a clean predetermined pattern.

[0070] The steps above omit details commonly performed during exposure, such as baking and post-exposure baking.

[0071] If you want to continuously transfer a photosensitive resin pattern, in step S6, perform scan exposure, in which the object to be exposed is continuously moved while the light from the light source is irradiated onto it. By moving the object to be exposed horizontally in the direction of the optical axis, a linear pattern can be exposed.

[0072] By following the steps described above, an irregular pattern can be transferred to the outer surface of the object to be exposed in a single step. [Examples]

[0073] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0074] [Example 1] A resist pattern was fabricated by exposure using the exposure apparatus shown in Figure 2. Figure 5 shows the results of observing with an optical microscope after applying a 1 μm thick positive resist TMER-ip3300 (Tokyo Ohka Kogyo Co., Ltd.) to a silicon wafer, changing the distance between the collimating lens and the silicon wafer to simulate step differences of 50 mm, 100 mm, 150 mm, and 200 mm in the optical axis direction relative to the reference plane (0 mm), exposing the wafer for the same exposure time, and then developing it.

[0075] For both the reference surface and each of the steps, under the same exposure conditions, it can be seen that the resist has holes approximately a few micrometers in size, and the silicon wafer beneath the resist is visible. This indicates that even when using an object with a step height of 200 mm, a fine pattern of resist with irregularly arranged holes of several micrometers on its surface can be exposed all at once.

[0076] As described above, using the exposure apparatus according to the present invention, fine patterns can be exposed to the reference surface and the surface of each step of an object to be exposed that has steps. As in the conventional method, fine patterns can also be exposed to the flat surface of an object to be exposed that does not have steps. Coherent light is directed onto a light-diffusing material, generating speckle light, which is scattered light with an irregular (random) arrangement and random light intensity. By positioning a collimating lens so that the light-diffusing material is approximately at the focal point relative to the spread speckle light, the light rays become parallel, and the speckle light intensity distribution pattern can be transferred to the reference surface and each of the steps of the object to be exposed, even if the object has large steps. [Explanation of Symbols]

[0077] 10 light source 20 Light Diffusing Member 30 Collimating Lenses 40 Exposed object holding part 50 Exposed object holder 60 Light Diffusion Member Support Section 100, 200 exposure equipment

Claims

1. An exposure apparatus that exposes an object to be exposed using speckle light, A light source that emits coherent light, A light diffusing member placed on the optical axis of the light source, A collimating lens that converts the speckle light scattered by the aforementioned light-diffusing member into parallel light, A collimating lens holder that allows the collimating lens to move in the optical axis direction, An exposure apparatus comprising an object to be exposed holding platform for holding the object to be exposed.

2. The exposure apparatus according to claim 1, wherein the collimating lens is detachable from and replaceable from the collimating lens holder.

3. The exposure apparatus according to claim 1 or 2, wherein the light diffusing member is detachable and replaceable.

4. The exposure apparatus according to claim 1 or 2, further comprising a density filter before or after the collimating lens on the optical axis.

5. The exposure apparatus according to claim 1 or 2, further comprising a homogenizing optical system between the collimating lens and the light diffusing member.

6. The exposure apparatus according to claim 1 or 2, further comprising a beam expander between the light source and the light diffusing member.

7. The exposure apparatus according to claim 1 or 2, comprising a reduction projection optical system between the light diffusing member and the collimating lens, wherein the collimating lens is positioned such that it has a focal point at the imaging position of the reduction projection optical system.

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