JP2006330085A - Method for manufacturing member having fine structure and exposure method used for the manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily form a submicron periodical fine structure on a curved surface. <P>SOLUTION: The method includes a preparation step of preparing a mask having a lattice pattern with a period P and an irradiation step of irradiating a member via the mask with light having a spectral width Δλ, wherein the distance (d) between the mask and the member is controlled to satisfy d≥2P<SP>2</SP>/Δλ in the irradiation step so as to obtain intensity distribution with a P/2 period on the member surface. Thereby, a submicron periodical fine structure can be easily formed on a curved surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a member having a fine structure, and an exposure method used for the method, and specifically to a method for manufacturing a member having a submicron periodic structure such as an antireflection structure, and a method for manufacturing the same. The present invention relates to an exposure method used.

  Optical elements that have been subjected to light reflection prevention are used in various applications. As a method of the antireflection treatment, for example, a technique of providing an antireflection layer comprising a low refractive index layer single layer film or a multilayer film of a low refractive index layer and a high refractive index layer by vapor deposition, sputtering, painting, or the like. It is general (patent document 1). However, the antireflection layer by vapor deposition or sputtering has problems in productivity and cost. In the method of forming the antireflection layer, the wavelength dependency is large, the antireflection effect outside the predetermined wavelength is small, and it is possible to realize a good antireflection effect in the entire visible light region required in an imaging system or the like. It is very difficult. In addition, there is a problem of angle dependency in which the antireflection effect is reduced as the incident angle is increased.

  It is known that the refractive index of a microstructure layer can be changed by adding a microstructure having a size equal to or smaller than the wavelength of incident light to the surface of the optical element (Non-patent Document 1). When a microstructure having a triangular wave shape in cross section having a period of less than the wavelength to prevent reflection and a height of 0.4 times or more the wavelength to prevent reflection is formed on the surface of the optical element, The rapid change in the refractive index of the light becomes smooth, and incident light can enter the optical element without generating unnecessary reflected light. Compared with the above-described antireflection treatment method comprising a multilayer film, the optical element antireflection treatment method for an optical element having a fine structure has a smaller wavelength dependency and an improved angle dependency (Non-Patent Document 2).

In order to realize an antireflection function for light in the visible light region with a fine structure, a processing method in the submicron region is required. As a method for forming such a fine structure in the submicron region, a photolithography technique, an X-ray lithography technique (Patent Document 3), a two-beam interference exposure technique (Non-Patent Document 3), an electron beam drawing technique (Patent Document 2), etc. There has been proposed a method of forming by combining the etching technique and the like. For example, by using a method such as electron beam (EB) drawing on the surface of an optical element material (for example, quartz glass), a mask having a submicron pitch pattern is directly formed and covered with the optical element material mask by dry etching. There is a method for finely processing a portion other than the above (Patent Document 2).
JP 2001-127852 A JP 2001-272505 A JP 56-26438 A Daniel H. G. Michael Morris, “Analysis of antireflection-structured surfaces with continuous one-dimensional surface. profiles), Applied Optics, Vol. 32, No. 14 (Vol. 32, No. 14), p. 2582-2598, 1993 Eric B. Gran (Eric B. Grann), M.M. G. MG Moharam, Drew A. Drew A. Pommet, “Optimal design for antireflective tapered two-dimensional subwavelength grating structures”, Journal of Optical Society of・ America A (Journal of the Optical Society of America A), Vol. 12, No. 2 (Vol. 12, No. 2), p. 333-339, 1995 Yuzo Ono, Yasuo Kimura, Yoshinori Ohta, Nobuo Nishida, “Anti-reflection Effect in Ultra High Spatial Holographic Gratings ultrahigh spatial-frequency holographic relief gratings ”, Applied Optics, Vol. 26, No. 6 (Vol. 26, No. 6), p. 1142-1146, 1987

  When a submicron periodic structure is added to the surface of an optical element having a curved surface such as a lens, no method has been proposed so far that satisfies all three points of processing to a curved surface, minimum resolution, and ease of processing. .

  For example, the photolithography technique has excellent minimum resolution, but requires a shallow depth of focus and a plane to be exposed.

  Further, in the X-ray lithography technique described in Patent Document 3, there are proposed a method in which exposure is performed with a mask or member in close contact with each other or a minute gap being opened, and a method in which exposure is performed with the mask and member separated. However, although the former is excellent in resolution, there is almost no working distance because the mask and the member are brought into close contact with each other or opposed to each other through a minute gap. For this reason, the member is required to have the same surface shape as the mask, and is practically limited to processing on a flat substrate. The latter can be applied to curved surface processing because the working distance is long and the surface shape is arbitrary, but the resolution is reduced because X-rays are diffracted in the mask.

  Although the two-beam interference exposure technology described in Non-Patent Document 3 can be processed to the surface of a curved surface, it is easily affected by vibration during exposure to the member, and a fine structure is stably formed on the member surface. It is not easy to do.

  The electron beam drawing technique described in Patent Document 2 requires that the surface of the member be a flat surface, and because it is a method of sequentially scanning the surface of the member, it takes time to create the member, which is on the order of several tens of square millimeters or more. This is not suitable for the production of optical elements that require a large area.

  Therefore, an object of the present invention is to provide a manufacturing method for easily forming a submicron periodic fine structure on a curved surface. Another object of the present invention is to provide an exposure method suitably used for this manufacturing method.

In order to achieve the above object, a manufacturing method of the present invention includes a preparation step of preparing a mask having a grating pattern of period P, and an irradiation step of irradiating a member with light having a spectral width of Δλ through the mask. In the irradiation step, the distance d between the mask and the member is d ≧ 2P ² / Δλ, thereby forming an intensity distribution having a period of P / 2 on the member surface.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method which forms easily a submicron periodic fine structure on a curved surface can be provided. Moreover, according to this invention, the exposure method used suitably for this manufacturing method can be provided.

(Principle explanation)
FIG. 1 is a schematic view showing an exposure method according to the embodiment. The exposure method according to the embodiment will be described with reference to FIG. In FIG. 1, a mask 11 and a member 12 are arranged to face each other. The member 12 is a substrate on which a fine structure is to be formed. Let d be the closest distance between the mask 11 and the member 12. The member 12 has a photosensitive material formed on the surface. Note that the member 12 itself may be formed of a photosensitive material. In FIG. 1, light emitted from a light source (not shown) passes through a mask 11 and is irradiated onto a member 12.

  FIG. 2 is a schematic diagram of an amplitude type mask according to the embodiment. The amplitude type mask includes a light absorbing portion 21 and a light transmitting portion 22. The light absorbing portion 21 and the light transmitting portion 22 are disposed in the effective area 23. The light absorbing portion 21 and the light transmitting portion 22 are arranged in a stripe shape with a period P. Each of the light absorbing portion and the light transmitting portion has a width P / 2, and the proportion of the effective area of the mask is 50%.

  First, the distance P between the mask 11 and the member 12 at the time of exposure will be described. Hereinafter, a case will be considered in which exposure is performed using monochromatic light having a wavelength λ having a high degree of spatial coherence as a light source, using the mask of FIG. When the distance d between the mask 11 and the member 12 is continuously changed, the intensity distribution on the surface of the member 12 is periodically increased by the propagation distance from the mask due to light diffraction and interference as shown in FIG. The pattern changes. FIG. 3 is a schematic diagram of a Talbot image.

In FIG. 3, the intensity pattern is the same intensity distribution (Talbot image) as the mask of period P → intensity distribution (Talbot sub-image) of half the period of the mask (P / 2) → intensity obtained by inverting the mask of period P Distribution (inverted Talbot image) → Talbot sub-image → Talbot image. The distance for one cycle in which the Talbot image is repeated (Talbot period) is 2P ² / λ.

  Here, when exposure is performed using a mask using a light source that oscillates a plurality of light beams having a plurality of different wavelengths, the Talbot period varies depending on the wavelength constituting the light source. That is, when the distance between the mask and the member surface is increased, the intensity distribution on the member surface is different for each wavelength. When two or more wavelengths are included in the spectrum width Δλ, the intensity distribution on the member surface is a distribution obtained by integrating different intensity distributions for each wavelength.

Here, a light source having a continuous spectrum is considered, and the wavelength of the short wavelength end of the light source is λ, and the wavelength of the long wavelength end is λ + Δλ. Considering a distance d between the mask and member distance d such that the Talbot period of wavelength λ + Δλ is more than one period compared to the Talbot period of wavelength λ.
d / (2P ² / λ) −d / (2P ² / (λ + Δλ)) ≧ 1,
And solving this,
d ≧ 2P ² / Δλ (1)
It becomes.
At a distance d satisfying the equation (1), light having a wavelength between the wavelength λ and the wavelength λ + Δλ creates all intensity distributions included in one Talbot period. Therefore, the result of integrating the intensity distributions that differ for each wavelength is equal to the result of integrating the intensity distribution for one Talbot period.

  FIG. 4 is a graph showing the intensity distribution of incident light immediately after transmitting through the mask. FIG. 5 is a graph showing an intensity distribution obtained by integrating one Talbot period. 4 and 5, the horizontal axis indicates a position based on the mask center in units of the pitch of the mask 11, and the vertical axis indicates a relative intensity distribution based on the maximum intensity of incident light. When light having the intensity distribution shown in FIG. 4 is incident on the member, an intensity distribution is formed on the member 12 by integrating the intensity distribution for one cycle of the Talbot. As apparent from FIG. 5, the period of the intensity distribution on the surface of the member 12 is P / 2.

FIG. 6 is a schematic diagram showing the distance from the mask and the light intensity distribution. FIG. 6 schematically shows the relationship between the distance from the mask and the light intensity distribution when continuous spectrum light enters the mask. Therefore, when the distance from the mask is 0, the intensity distribution 61 immediately after transmitting through the mask is represented. In FIG. 6, when d ≧ 2P ² / Δλ, the light intensity distribution in the direction perpendicular to the light propagation direction is a triangular wave intensity distribution 62 with a period of P / 2.

As described above, when the exposure method according to the embodiment is used, if the distance between the mask and the member satisfies d ≧ 2P ² / Δλ, the intensity distribution has a substantially constant period regardless of the distance between the mask and the member. It can be seen that can be obtained. In other words, even if the surface of the member has a curved shape where the distance between the mask and the surface of the member is not constant, an intensity distribution having a constant period can be obtained by using the exposure method of the embodiment. Actually, if the d distance is greatly separated from the mask and the member, high performance is required for the size of the light source, spatial coherence and the like. For this reason, the distance between the mask and the member is desirably 10 ⁶ times or less of the wavelength λ included in the light source.

  Next, the wavelength of the light source will be described. The above exposure method has the same effect without depending on the wavelength used for exposure. Therefore, it is possible to carry out the above-described exposure method using near infrared light, visible light, ultraviolet light, X-ray light or the like having a wavelength of 1 μm or less. Light having a wavelength of 1 μm or less is particularly effective because it can form a structure of a submicron region or less where conventional cutting and grinding are difficult.

  Next, the spectrum of the light source will be described. Most preferably, the spectrum of the light source is a continuous spectrum. As light sources having such properties, there are supercontinuum light generated by using synchrotron radiation light having a high spatial coherence and a wide continuous spectrum or a short pulse laser. As a light source that realizes a pseudo continuous spectrum, there is a multi-wavelength laser beam. A similar effect can be obtained even with a light source that includes light of two or more wavelengths in the range of the spectral width Δλ.

FIG. 7 is a graph showing the result of simulating changes in the distance from the mask and the light intensity distribution when a light source including light of five wavelengths is used. FIG. 8 is a graph showing the results of simulating changes in the distance from the mask and the light intensity distribution when a light source including light of 33 wavelengths is used. In the case of the five wavelengths shown in FIG. 7, it can be seen that although d ≧ 2P ² / Δλ, there is a fluctuation in amplitude, but the intensity distribution has a period of P / 2. In the case of the 33 wavelengths in FIG. 8, it can be seen that there is almost no fluctuation in amplitude when d ≧ 2P ² / Δλ, and the intensity distribution has a period of P / 2.

Next, the shape of the fine structure formed by exposure will be described. FIG. 9A is a schematic diagram showing an exposure method when a fine structure is formed on a flat substrate, and FIG. 9B is a cross-sectional view of the flat substrate on which the fine structure is formed. In FIG. 9A, the member 91 has a flat plate shape and is arranged to face the mask 11 with a distance d. Here, the distance d satisfies d ≧ 2P ² / Δλ. When developed after exposure under these conditions, a fine shape is formed on the surface of the member as shown in FIG. The member to which the fine structure 92 is added corresponds to the intensity distribution shown in FIG. 5, and the period of the fine structure is P / 2. A microstructure having a triangular wave cross section is suitable for the purpose of preventing reflection of an optical member, and a fine shape suitable for preventing reflection can be realized by a single exposure by the exposure method of the embodiment.

Although the member shown in FIG. 9 was a planar shape, it is not restricted to this. That is, in the exposure method of the embodiment, as long as d ≧ 2P ² / Δλ is satisfied, even if the distance between the mask and the member is changed, the change in the intensity distribution is small, so that the distance between the mask and the member surface is not constant. Even when the surface is a member having a curved surface shape such as a spherical surface, an aspherical surface, a cylindrical surface, or a free-form surface, exposure for forming a fine structure can be performed. In addition, even if the surface is a concave surface, a convex surface, or a surface including both concave and convex surfaces, exposure for forming a fine structure can be performed.

  The surface of the member to which the fine structure is to be added is optimally the surface close to the light source (the surface on the opposite side). When a fine structure is to be formed on a surface far from the light source of the member, the internal loss of light of the exposure light source inside the member becomes a problem. If the internal loss is not large, a fine structure can be formed even on a surface far from the light source.

FIG. 10A is a schematic diagram showing an exposure method when a fine structure is formed on the spherical lens, and FIG. 10B is a cross-sectional view of the spherical lens on which the fine structure is formed. In FIG. 10A, the member 101 has a convex spherical lens shape, and is disposed opposite to the mask 11 with a distance d at the shortest portion. Here, the distance d satisfies d ≧ 2P ² / Δλ. When developed after exposure under these conditions, a spherical lens 102 having a fine shape formed on the surface of the member as shown in FIG. 10B is obtained. Thus, it is shown that if the distance that the mask 11 is closest to satisfies the condition of d ≧ P ² / Δλ, a fine structure with a period of P / 2 can be formed over the entire member irradiation surface.

  Next, the grating period P of the mask that can be used for exposure will be described. The mask period must be P ≧ λ because light (wavelength: λ) contained in the exposure light source must be able to pass through. Further, when the exposure method of the present invention is used for processing in the submicron region, it is necessary that P / 2 ≦ 1 μm, that is, P ≦ 2 μm.

  Next, the light intensity ratio of the light transmitting portion of the mask and the light shielding portion immediately after transmitting through the mask will be described. FIG. 11 is a graph showing the result of simulating changes in the distance from the mask and the light intensity distribution when a mask having a mask contrast of 2 is used. FIG. 12 is a graph showing the results of simulating changes in the distance from the mask and the light intensity distribution when a mask having a mask contrast of 5 is used.

  FIG. 11 shows the distance d from the mask and the intensity distribution when the light intensity of the light transmitting portion immediately after transmitting the mask shown in FIG. 2 is 1 and the light intensity of the light shielding portion is 0.5 (mask contrast 2). The result of simulating the relationship is shown. Similarly, FIG. 12 shows the relationship between the distance d from the mask and the intensity distribution when the light intensity of the light transmitting part immediately after transmission through the mask is 1 and the light intensity of the light shielding part is 0.2 (mask contrast 5). The simulation result is shown.

  Here, the mask contrast represents the light intensity ratio of the light transmitting part immediately after the mask and the light intensity of the light shielding part immediately after the mask, and (maximum light intensity of the light transmitting part immediately after the mask) / (light shielding immediately after the mask). Part minimum light intensity). Considering FIGS. 11 and 12, etc., the mask contrast needs to be at least 2 (FIG. 11), preferably 5 or more (FIG. 12). When the mask contrast is less than 2, the contrast of the intensity distribution on the member surface is lowered, and a fine structure cannot be formed on the member surface.

  Next, the composition area ratio of the light transmitting part and the light shielding part of the mask will be described. FIG. 13 is a schematic diagram of an amplitude type mask having a light transmission area of 75%. FIG. 14 is a graph showing the results of simulating changes in the distance from the mask and the light intensity distribution when a mask having a light transmission area of 75% is used.

  If the area of the light transmitting portion of the mask exceeds 50% of the effective area, the intensity distributions adjacent to each other overlap on the member surface, and the contrast deteriorates. As can be seen from FIG. 14, it can be seen that the contrast is reduced as compared with the case where the area of the transmission part shown in FIG. 8 is 50%. In order to obtain good contrast, it is necessary to make the light transmission area of the mask less than 75%.

  Hereinafter, an example of a mask manufacturing method will be described. First, an absorbing material containing one or more of Ta, Ni, Au, Cu, Ag, Cr, and Fe elements that absorb light from a light source on a flat substrate that transmits light from the light source such as quartz glass. An absorbing layer is formed on the surface of the member by sputtering or the like. Next, the absorption layer of the light transmission part is removed using an electron beam drawing apparatus. By this method, a mask having a desired light absorption part can be manufactured.

  Although the exposure method of the embodiment has been described above, the above description is an example, and the present invention is not limited to this. For example, although the embodiments have been described using the amplitude modulation type mask, the same effect can be obtained not only with the amplitude modulation type but also with a phase modulation type mask or an amplitude phase modulation type mask.

  In the embodiment, the case where the mask modulation is binary has been described, but the present invention is not limited to this. Under the condition that the modulation period is P, the mask modulation may be multi-value of three or more values or continuous modulation. In these cases, the intensity distribution on the surface of the member may be different, but the period of the intensity distribution is P / 2, and the same effect as the embodiment is achieved.

  In the embodiment, a mask made of a one-dimensional grating has been described. However, a mask made of a two-dimensional grating that modulates incident light in a two-dimensional direction may be used. A two-dimensional lattice is composed of two or more independent lattice vectors, and can be considered as decomposed into a one-dimensional lattice. Therefore, even if the period of each one-dimensional grating is the same or different from each other, the point that the period of the light intensity distribution on the member surface is halved remains the same.

  With the above exposure method, various microstructures can be produced on the member. Such a fine structure can be used not only for an antireflection structure for the purpose of preventing reflection of an optical member but also for imparting characteristics that the material of the optical member does not originally have. For example, when an anisotropic microstructure is added to the surface of an optical member having no anisotropy, the effect of a polarizing element such as a wave plate, a polarizing plate, a polarizing beam splitter, or a polarizing mirror can be obtained. . Further, for example, when used for measurement or observation, it can be used from the radio wave region to the gamma ray region without being limited by the wavelength. Furthermore, since the embodiment is a technique that utilizes the nature of waves, it can be applied even to sound waves.

As described above, according to the fine structure manufacturing method of the embodiment, a submicron fine periodic structure can be easily formed on the surface of an optical member having a curved shape or a light absorber. In particular, by using the exposure method according to the embodiment, the distance d between the mask and the surface of the member satisfies d ≧ 2P ² / Δλ even if the surface of the member has a curved shape where the distance between the mask and the surface of the member is not constant. If so, it is possible to form a fine periodic structure having a constant period P / 2 that is half the period P of the mask. Further, according to the fine structure manufacturing method of the embodiment, the mask period is twice as long as the desired period, so that the mask can be easily formed. Furthermore, according to the fine structure manufacturing method of the embodiment, since the distance between the mask and the member is large, productivity can be improved as compared with the method of exposing the mask and the member in close contact with each other or by opening a minute gap. Can do. In addition, according to the fine structure manufacturing method of the embodiment, the light intensity distribution on the member surface continuously changes due to diffraction and interference, so that a continuous triangular wave shape can be obtained by one exposure. it can.

Example 1
With reference to FIG. 15, the manufacturing method of the fine structure of Example 1 is demonstrated. 15A to 15C are schematic views of a method for forming a fine structure on a flat substrate according to the first embodiment. In FIG. 15, first, an amplitude type X-ray mask 151 that is a one-dimensional lattice as shown in FIG. 15A is prepared. The mask 151 was formed by forming an absorption layer having a thickness of 1 μm on a silicon carbide (SiC) substrate by sputtering and removing Ta in the X-ray transmission part by an electron beam drawing apparatus. In the mask 151, the size of the effective region 152 is 20 mm × 20 mm, and the widths of the X-ray transmission part 153 and the X-ray shielding part 154 are both 200 nm.

  Next, exposure was performed with the mask 152 facing a member 152 of a transparent flat substrate of PMMA (acrylic resin) having a size of 30 mm × 30 mm. As shown in FIG. 15B, X-rays were irradiated from an X-ray light source using synchrotron radiation. The center wavelength of the X-ray light source is 0.36 nm, and the spectrum width is 0.36 nm. The spectral distribution of the X-ray light source is a Gaussian distribution, and the distance d between the mask 151 and the member 152 is 1.5 mm. Under the above conditions, the member was exposed to X-rays from above the member 152. The exposure amount was 10 A · min. After exposure, the member 156 having a one-dimensional periodic microstructure with a period of 200 nm and a height of 400 nm on the upper surface of the member is immersed in a developer mainly composed of 2- (2-n-butoxyethoxy) ethanol for 3 minutes. Was made.

  The reflectance of the member 156 formed with a fine structure was 0.1% or less including reflected and scattered light when measured using He-Ne laser light which is linearly polarized light. Note that the polarization direction of the He—Ne laser light used for the measurement was measured in parallel with the lattice vector of the periodic structure of the member. Even when exposure is performed with the member inclined at ± 5 ° with respect to the mask during exposure and the distance between the mask and the member closest to 1.5 mm is exposed, the upper surface of the member is the same as when exposure is performed with the mask and member parallel. In addition, a one-dimensional periodic microstructure having a period of 200 nm and a height of 400 nm could be formed.

(Example 2)
A method for manufacturing a fine structure according to Example 2 will be described. 16A to 16D are schematic views of a method for forming a two-dimensional microstructure on a planar substrate according to the second embodiment. In Example 2, the same light source, mask 151, and member 152 as in Example 1 were used for exposure. Similar to Example 1, the member 152 was placed so that the distance d of the mask 151 was 1.5 mm, and the surface of the member was exposed to X-rays under the same conditions as in Example 1. FIG. 16A is a schematic diagram showing a mask 151 similar to that in FIG. FIG. 16B shows the exposure amount distribution on the surface of the member 161 after the first exposure is completed. In FIG. 16B, a portion that is strongly exposed by the first exposure is indicated by 161.

  Next, the direction of the member 161 was rotated 90 degrees, and the second exposure was performed under the same exposure conditions as the first. FIG. 16C is a schematic view showing the exposure amount distribution on the member surface after the second exposure is completed. A portion that is strongly exposed by the first and second exposures is indicated by 162, and a portion that is strongly exposed by the first or second exposure is indicated by 163. The member 161 was developed by the same developing method as in Example 1 to produce a member 164 having a two-dimensional periodic structure with a period of 200 nm and a height of 400 nm formed on the surface of the member 161 (FIG. 16D). The reflectance of the member 164 having a fine structure was 0.1% or less including reflected / scattered light when measured using He-Ne laser light which is circularly polarized light.

(Example 3)
A method for manufacturing a fine structure according to Example 3 will be described. FIG. 17A is a schematic diagram of a spherical lens on which a fine structure is formed, and FIG. 17B is a schematic diagram of the spherical lens according to the third embodiment. In Example 3, a fine structure having a two-dimensional periodic pattern with a period of 200 nm and a height of 400 nm was formed on a spherical member surface 171 using the same exposure method and development method as in Example 2. The diameter of the member was 25 mm, and the sag amount of the lens in the irradiated area was 2 mm. As shown in FIG. 17A, the member 171 was placed so that the spherical surface of the member 171 faced upward, and the distance between the member and the mask closest to the mask was 1.5 mm or more, and X-ray exposure was performed. After the exposure, the member 171 was developed, and a fine structure having a two-dimensional periodic pattern with a period of 200 nm and a height of 400 nm was formed on the spherical surface of the member 171. When the reflectance of the spherical lens 172 to which the fine structure was added was measured using He-Ne laser light which is circularly polarized light, it was 0.1% or less including the reflected scattered light.

Example 4
A method for manufacturing a fine structure according to Example 4 will be described. FIG. 18A is an aspheric lens exposure method according to Example 4, and FIG. 18B is a schematic diagram of the aspheric lens on which a fine structure is formed. Using the same exposure method and development method as in Example 3, a fine structure having a two-dimensional periodic pattern with a period of 200 nm and a height of 400 nm was formed on the aspheric surface of the aspherical member 181. The diameter of the member was 25 nm, and the sag amount of the lens in the irradiated area was 2 mm. The reflectance of the member 182 formed with the fine structure was 0.1% or less including reflected and scattered light when measured using He-Ne laser light which is circularly polarized light.

(Example 5)
A method for manufacturing a fine structure according to Example 5 will be described. Using the same exposure method and development method as those in Embodiment 3, a fine structure having a two-dimensional periodic pattern with a period of 200 nm and a height of 400 nm was formed on the surface of a black PMMA (acrylic resin) sheet. The reflectance of the black PMMA (acrylic resin) sheet having a fine structure was 0.1% or less including reflected and scattered light when measured using He-Ne laser light which is circularly polarized light. This black PMMA sheet can be used as an antireflection additive by attaching it to other members. Here, the antireflection additive is a member having an antireflection effect, and the member having the antireflection effect is joined to a part or all of another member to be antireflected, and a desired reflection is applied to the member to be antireflection. It is a member intended to add a prevention effect.

(Example 6)
A method for manufacturing a fine structure according to Example 6 will be described. FIG. 19A is a schematic cross-sectional view of a lens barrel part in which a fine structure is formed, and FIG. 19B is a schematic cross-sectional view of a lens barrel in which a lens barrel part in which a fine structure is formed. Using the same exposure method and development method as in Example 3, a fine structure was added to a lens barrel part formed of black PMMA (acrylic resin). First, a lens barrel part obtained by dividing a cylindrical lens barrel having a diameter of 15 mm into three parts every 120 degrees was manufactured by resin molding, and a fine structure having a two-dimensional periodic pattern of 200 nm and a height of 400 nm was added to the inside of each part. FIG. 19A shows a lens barrel part to which a fine structure is added. A resin barrel was manufactured by bonding the three parts together (FIG. 19B). The reflectance of the lens barrel formed with the fine structure was 0.1% or less including reflected and scattered light when measured using He-Ne laser light which is circularly polarized light. When a lens was inserted into a fine-structured lens barrel and examined for flare light, it showed extremely good characteristics compared to conventional microtechnology.

(Example 7)
A method for manufacturing a fine structure according to Example 7 will be described. FIG. 20A is a schematic view of an amplitude type mask that is a two-dimensional lattice, and FIG. 20B is a schematic view of a planar substrate on which a fine structure is formed. In manufacturing the microstructure of Example 7, the same members as in Example 1 were used. In FIG. 20A, a mask 201 is an amplitude type mask having a two-dimensional lattice. The period of the mask 201 is 400 nm in both directions orthogonal to each other. The member was set so that the distance d between the member and the mask was 1.5 mm, and the surface of the member was exposed to X-rays under the same conditions as in Example 1. The member was developed by the developing method used in Example 1, and a fine structure having a two-dimensional periodic pattern with a period of 200 nm and a height of 400 nm was formed on the surface of the member (FIG. 20B). The reflectance of the member 202 having a fine structure was 0.1% or less including reflected and scattered light when measured using He-Ne laser light which is circularly polarized light.

  The present invention is suitable for an optical element having an optical function surface that requires antireflection processing for light rays in an optical path, such as a lens element and a prism element used in a digital camera, a printer device, and the like. In addition, the present invention can be applied to a structural member used for holding these optical elements or a casing member that protects the entire apparatus including the optical elements, thereby providing an antireflection surface that prevents unnecessary light. Furthermore, the present invention relates to various devices such as light emitting elements such as semiconductor laser elements and light emitting diodes, light receiving elements such as photodiodes, imaging elements such as CCD and CMOS, optical switches and branching devices used for optical communication, The function of each device can be improved by forming it in a portion requiring antireflection treatment. Furthermore, the present invention may be applied to a display portion of a display panel such as a liquid crystal display panel, an organic electroluminescence panel, or a plasma light emitting panel. In addition, the present invention can be widely applied to all members that require an antireflection treatment used in optical equipment. The present invention is also applicable to polarizing elements such as a wave plate, a polarizing plate, a polarizing beam splitter, and a polarizing mirror.

Schematic showing the exposure method according to the embodiment Schematic diagram of amplitude-type mask according to an embodiment Schematic image of the Talbot image Graph showing intensity distribution of incident light immediately after transmitting through mask Graph showing the intensity distribution that integrates one Talbot period Schematic showing distance from mask and light intensity distribution It is a graph which shows the result of having simulated the change from the distance from a mask when using the light source containing light of 5 wavelengths, and light intensity distribution. The graph which shows the result of having simulated the distance from a mask and the change of light intensity distribution when using the light source containing the light of 33 wavelengths (A) is schematic which shows the exposure method when forming a fine structure in a planar substrate, (b) is sectional drawing of the planar substrate in which the fine structure was formed (A) is schematic which shows the exposure method when forming a fine structure in a spherical lens, (b) is sectional drawing of the spherical lens in which the fine structure was formed The graph which shows the result of having simulated the change from the distance from a mask, and light intensity distribution when using the mask of mask contrast 2 , A graph showing the result of simulating changes in the distance from the mask and the light intensity distribution when using a mask with a mask contrast of 5 Schematic diagram of an amplitude mask with a light transmission area of 75% The graph which shows the result of having simulated the change from the distance from a mask and light intensity distribution when using the mask whose light transmission part area is 75% (A)-(c) is the schematic of the method of forming a fine structure in the plane substrate concerning Example 1. FIG. (A)-(d) is schematic of the method of forming a two-dimensional fine structure in the plane substrate concerning Example 2. FIG. (A) is the exposure method of the spherical lens concerning Example 3, (b) is the schematic of the spherical lens in which the fine structure was formed (A) is the exposure method of the aspherical lens concerning Example 4, (b) is the schematic of the aspherical lens in which the fine structure was formed (A) is a schematic cross-sectional view of a lens barrel part in which a fine structure is formed, and (b) is a schematic cross-sectional view of a lens barrel in which a lens barrel part in which a fine structure is formed is assembled. (A) is a schematic diagram of an amplitude type mask which is a two-dimensional lattice, and (b) is a schematic diagram of a planar substrate on which a fine structure is formed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Mask 12 Microstructure forming member 21 Light shielding part 22 Light transmitting part 23 Mask effective area 61 Intensity distribution 62 immediately after mask transmission Triangular wave intensity distribution 91 with period P / 2 Planar substrate 92 A fine structure is formed Planar substrate 101 Spherical lens 102 Spherical lens 151 with fine structure 151 Mask 152 Mask effective area 153 Light transmitting portion 154 Light shielding portion 155 Planar substrate 156 Planar substrate 161 with fine structure Strong exposure by the first exposure The portion 162 that has been exposed strongly by the first and second exposures 163 The portion 164 that has been strongly exposed by the first or second exposure 164 The planar substrate 171 on which the two-dimensional periodic structure is formed The spherical lens 172 The fine structure is formed Spherical lens 181 Aspherical lens 182 Aspherical lens 191 with fine structure formed Fine structure Planar substrate having a fine structure is formed by the formed barrel component 201 2-dimensional grating mask 202 two-dimensional grating mask

Claims (25)

Preparing a mask having a grating pattern of period P;
An irradiation step of irradiating the member with light having a spectral width of Δλ through the mask,
An exposure method in which, in the irradiation step, an intensity distribution with a period of P / 2 is formed on the surface of the member by setting a distance d between the mask and the member to be d ≧ 2P ² / Δλ.   The exposure method according to claim 1, wherein in the irradiation step, the member is a material including a material sensitive to a wavelength of a light source.   The exposure method according to claim 1, wherein in the irradiation step, the light includes a wavelength of 1 μm or less.   2. The exposure method according to claim 1, wherein, in the irradiation step, the light includes a continuous spectrum or a spectrum of five or more wavelengths within a spectrum width Δλ.   2. The exposure method according to claim 1, wherein in the preparation step, the mask has a lattice pattern having a period P of 2 μm or less.   The exposure method according to claim 1, wherein in the preparing step, a mask having a lattice pattern in which the wavelength included in the light is λ and the period P is P ≧ λ is used. The exposure method according to claim 1, wherein in the irradiation step, a distance d between the mask and the member is 10 ⁶ times or less of a wavelength λ included in the light.   The exposure method according to claim 1, wherein, in the irradiation step, the exposure method is used for a member having a surface shape in which a distance d between the mask and the member is not constant depending on a position on the surface of the member.   The exposure method according to claim 1, wherein the exposure method according to claim 1 is used a plurality of times.   The manufacturing method of the member which has a fine structure which forms a fine structure in the said member by developing the said member following the exposure method of Claim 1.   The method for manufacturing a member having a microstructure according to claim 10, wherein the microstructure is formed on a concave surface, a convex surface, or a surface including both concave and convex surfaces.   The microstructure is an antireflection structure having a period equal to or less than a wavelength of light to suppress reflection and a height of 0.4 or more times the wavelength of light to prevent reflection. A method for producing a member having the microstructure according to 10.   The method for manufacturing a member having a microstructure according to claim 10, wherein the microstructure has anisotropy and causes the member to function as a polarizing element.   The exposure method according to claim 1, wherein in the irradiation step, the mask is an amplitude modulation mask.   15. The exposure method according to claim 14, wherein the ratio of the minimum light transmittance and the maximum light transmittance of the mask is 1: 2 or more.   16. The exposure method according to claim 15, wherein the ratio of the minimum light transmittance to the maximum light transmittance of the mask is 1: 5 or more.   The area of a region having a light transmittance of at least half of the sum of the minimum light transmittance and the maximum light transmittance of the mask in the effective region having a periodic lattice structure of the mask is 75% or less. The exposure method as described.   The area of the region having a light transmittance equal to or more than half of the sum of the minimum light transmittance and the maximum light transmittance of the mask in the effective region having a periodic lattice structure of the mask is 50% or less. Exposure method.   The exposure method according to claim 14, wherein the mask is a mask formed of a slit pattern having a period P.   2. The exposure method according to claim 1, wherein, in the preparation step, the mask includes a grating in which the light absorbing material is formed with a period of twice or less the wavelength of light to be prevented from being reflected.   The exposure method according to claim 1, wherein in the preparation step, the mask is a phase modulation mask.   The exposure method according to claim 1, wherein in the preparation step, the mask is a phase amplitude modulation mask.   The exposure method according to claim 1, wherein in the preparing step, the mask is a mask including a one-dimensional periodic grating.   The exposure method according to claim 1, wherein in the preparation step, the mask is a mask including a two-dimensional periodic grating composed of two or more grating vectors. 2. The exposure method according to claim 1, wherein in the preparation step, the mask has a grating having different periods in different directions.

Images