JP2005132679A - Manufacturing method of optical element having non-reflective structure and optical element having non-reflective structure manufactured through the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical element having a non-reflective structure whereby the high-precision optical element having the non-reflective structure can be repetitively molded without causing pattern displacement over a large area. <P>SOLUTION: A cylindrical Cr mask with a diameter of 0.15 μm is formed on the surface of a quartz glass substrate. The quartz glass substrate onto which the cylindrical Cr mask is formed is introduced into an RF dry etching device, and its surface is subjected to dry etching to form a conical non-reflective structure with a pitch of 0.15 μm and a height of 0.15 μm on the surface of the quartz glass substrate. A thin film for surface protection is formed on the surface of the mold material, and a mold 3 for molding the non-reflective structure is prepared. An optical material 11, onto which a mold release agent 16 containing carbon (C) particulates is applied for mold release, is press-molded using the mold 3. The mold 3 is released from the optical material 11 without cooling. The mold release agent 16 is removed after the press-molded optical material 11 is cooled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an optical element having a highly accurate non-reflective structure that does not cause pattern shift over a large area, and an optical element having a non-reflective structure manufactured by the method.

  In order to prevent surface reflection of the optical element, a method of forming a non-reflection structure on the surface of the optical element has been proposed. The proposed non-reflective structure has a very fine uneven shape with a submicron pitch and an aspect ratio of 1 or more. As a method for forming such a fine structure, a fine processing method using dry etching has been proposed.

  On the other hand, as an effective method for manufacturing a high-precision optical element in a large amount and at a low cost, a method of press-molding an optical material (molding material) made of glass or resin has been proposed.

When an optical material made of heat-softened glass or resin is press-molded using a mold, the optical material is difficult to release from the mold, so a special release film may be formed on the surface of the mold. A mold release agent is applied for each molding shot, so that the mold release is facilitated. In particular, when glass is used as the optical material, a very special coating is applied to the surface of the mold. For example, Patent Document 1 discloses a technique in which a cemented carbide or cermet containing WC as a main component is used as a mold material, and a surface of a mold manufactured using the mold material is coated with a noble metal protective film. Has been. By using the mold having such a configuration, it is possible to mass-produce optical elements by press molding. Moreover, in the metal mold | die of patent document 2, the film thickness of 10 nm or less is provided on the optical function surface of the metal mold body made of boron nitride, chromium nitride, chromium carbide, chromium oxide, silicon carbide, carbon, platinum or cemented carbide. By forming a carbon film having the above, release properties from glass are improved.
Japanese Examined Patent Publication No. 62-28091 JP-A-6-305742

  However, in the case of a microfabrication method using dry etching, depending on the optical material to be used, the surface becomes very rough after etching or the etching rate becomes very slow, which limits the usable optical materials. . That is, the optical material that can be used is limited to quartz glass or the like, and it is not possible to use multicomponent glass or resin used in optical devices designed with various optical constants. For this reason, even if an optical element having a non-reflective structure is produced by a fine processing method using dry etching, a desired selectivity cannot be obtained, and an optical element having a non-reflective structure having a large aspect ratio cannot be obtained. . In addition, since the reproducibility of etching is low, there is a problem that the production cost is remarkably increased due to a decrease in yield and a decrease in mass productivity.

  Further, when press-molding an optical element having a non-reflective structure, in the conventional press-molding method, when the heated and softened optical material is cooled in a state of being in contact with the mold (pressed state), the mold and the optical material are Thermal stress is generated due to the difference in coefficient of thermal expansion, and as a result, the accuracy of the pattern transferred to the optical material is lowered. In particular, as the distance from the center of the mold increases toward the outer periphery, the shift of the pattern transferred to the optical material increases, so that a fine uneven pattern cannot be accurately transferred over a large area. For this reason, it is necessary to release the mold from the optical material obtained by press molding without cooling.

  However, as an optical material, a surface of a mold produced by using a cemented carbide or cermet mainly composed of WC described in Patent Document 1 as a mold material is coated with a noble metal-based protective film. When press-molding glass, the mold-to-glass releasability is quite good, but the mold cannot be released from the press-molded glass without cooling, and has an anti-reflective structure. The element cannot be molded precisely. In addition, if a mold having a carbon film described in Patent Document 2 is used, the mold can be released without cooling, but the material of the mold body can be processed into a concavo-convex shape with a non-reflective structure. It is very difficult.

  The present invention has been made to solve the above-described problems in the prior art, and it is possible to repeatedly mold an optical element having a high-precision non-reflective structure that does not cause pattern displacement over a large area. An object of the present invention is to provide a method for manufacturing an optical element having an antireflective structure, and an optical element having an antireflective structure manufactured by the method.

  In order to achieve the above object, the first method of manufacturing an optical element having an antireflection structure according to the present invention is excellent in high temperature strength, heat resistance, and non-reflection on a mold material with less surface roughness due to dry etching. After forming the non-reflective structure on the surface of the mold material by forming a mask corresponding to the structure and performing dry etching, a thin film for surface protection is formed on the surface of the mold material, and non-reflective A mold for structural molding is manufactured, and the optical material coated with a release agent for mold release is press-molded using the non-reflective structural mold, and the non-reflective structural mold is cooled without cooling. A mold is released from the press-molded optical material, the press-molded optical material is cooled, and then the release agent is removed.

  The second method for manufacturing an optical element having an antireflective structure according to the present invention is a mask corresponding to an antireflective structure in a mold material having excellent high temperature strength, heat resistance, and less surface roughness due to dry etching. After forming the nonreflective structure on the surface of the mold material by dry etching, a carbon (C) film or boron nitride is formed on the surface of the mold material as a thin film for mold release. (BN) A film is formed to produce a non-reflective structure molding die, the optical material is press-molded using the non-reflective structure molding die, and the non-reflective structure molding die is cooled without cooling. A mold is released from the press-molded optical material, and the press-molded optical material is cooled.

  The third method for manufacturing an optical element having an antireflective structure according to the present invention is a mask corresponding to an antireflective structure in a mold material having excellent high temperature strength, heat resistance, and less surface roughness due to dry etching. And forming the antireflective structure on the surface of the mold material by dry etching, forming a thin film for surface protection on the surface of the mold material, and forming the antireflective structure mold In an atmosphere in which an inert gas is mixed with a gas or mist-like liquid containing carbon (C) or fluorine (F) in a constituent molecule, using the non-reflective structure molding die, The optical material is press-molded, the non-reflective structure molding die is released from the press-molded optical material without cooling, and the press-molded optical material is cooled.

In the first to third manufacturing methods of the optical element having the non-reflective structure according to the present invention, the mold material is made of SiO ₂ film or Si film on quartz glass, silicon, Ni alloy, and cemented carbide. It is preferably one selected from the group consisting of those formed.

  In the first to third manufacturing methods of the optical element having the nonreflective structure of the present invention, the optical material is preferably multicomponent glass or resin.

  In the first to third manufacturing methods of the optical element having the nonreflective structure according to the present invention, the mask material corresponding to the nonreflective structure is selected from the group consisting of Cr, Ni, Au, and C. It is preferable that it is one.

  In the first to third manufacturing methods of the optical element having the non-reflective structure according to the present invention, the mask corresponding to the non-reflective structure is a columnar or polygonal column mask, and has a pitch equal to or less than a use wavelength. It is preferably formed in an array.

  In the first to third methods for manufacturing an optical element having a non-reflective structure according to the present invention, a resist is formed on the mask corresponding to the non-reflective structure, and electron beam lithography, X-ray lithography, or interference exposure is used. The resist is cylindrical or polygonal columnar by photolithography, and is patterned into an array with a pitch equal to or less than the wavelength used, and by wet etching or dry etching, the mask is cylindrical or polygonal columnar, It is preferable to form an array with a pitch equal to or shorter than the wavelength used.

  In the first or third method for manufacturing an optical element having a non-reflective structure according to the present invention, the thin film for surface protection is made of Pt, Pd, Ir, Rh, Os, Ru, Re, W, and Ta. It preferably contains at least one metal selected from the group consisting of:

  In the first or third method for manufacturing an optical element having a nonreflective structure according to the present invention, the mask material corresponding to the nonreflective structure is preferably a resist for X-ray lithography. In this case, it is preferable that the surface shape of the non-reflective structure molding die is a curved surface.

  In the first or third method for manufacturing an optical element having a non-reflective structure according to the present invention, the mask corresponding to the non-reflective structure is a conical or polygonal pyramid mask, and is obtained by X-ray lithography. It is preferably formed in an array with a pitch equal to or shorter than the wavelength used. In this case, it is preferable that the surface shape of the non-reflective structure molding die is a curved surface.

  In addition, the configuration of the optical element having the nonreflective structure according to the present invention is manufactured by the first to third manufacturing methods of the optical element having the nonreflective structure of the present invention.

  According to the present invention, the non-reflective structure molding die can be released from the press-molded optical material without cooling, so that the non-reflective structure mold and the optical material to be press-molded Generation of thermal stress due to the difference in thermal expansion coefficient can be prevented, and the accuracy of the pattern transferred to the optical material can be increased. As a result, it is possible to repeatedly mold an optical element having a highly accurate non-reflective structure that does not cause pattern deviation over a large area. In addition, according to the present invention, since the optical element is manufactured by press molding using a non-reflective structure molding die, an optical element having a non-reflective structure can be molded with good reproducibility. As a result, mass productivity is dramatically improved, and production costs can be significantly reduced.

  Hereinafter, the present invention will be described more specifically using embodiments.

[First Embodiment]
In the present embodiment, as an optical element having a non-reflective structure according to the present invention, a flat plate optical element having a conical microstructure with a pitch of 0.15 μm and a depth of 0.15 μm on one side will be described as an example.

  FIG. 1 is a cross-sectional view showing a press mold for an optical element having a non-reflective structure.

  In FIG. 1, 1 is a quartz glass substrate of 20 mm × 20 mm × 5 mm. Quartz glass is a material having excellent high-temperature strength, heat resistance, and less surface roughness due to dry etching. A conical non-reflective structure 2 having a pitch of 0.15 μm and a height of 0.15 μm is formed on the surface (press surface) of the quartz glass substrate 1, and the quartz glass substrate 1 on which the non-reflective structure 2 is formed. Is used as the non-reflective structure molding die 3.

Hereinafter, a method for producing the non-reflective structure molding die 3 will be described with reference to FIG. As shown in FIG. 2A, first, the surface (press surface) of the quartz glass substrate 1 was processed smoothly (Ra about 2 nm) by high-precision grinding and polishing. Next, as shown in FIG. 2B, a Cr film 20 having a thickness of 0.1 μm was formed on the surface (pressed surface) of the quartz glass substrate 1 processed smoothly using a sputtering method. Next, as shown in FIG. 2C, a PMMA resist 21 having a thickness of 0.3 μm was formed on the surface of the Cr film 20 by using a spin coating method. Next, as shown in FIG. 2D, a cylindrical pattern 22 made of PMMA resist and having a diameter of 0.15 μm was formed at a pitch of 0.15 μm on the surface of the Cr film 20 by using an EB (electron beam) drawing method. . Next, as shown in FIG. 2E, the Cr film 20 is wet-etched to form a cylindrical pattern made of Cr corresponding to the non-reflective structure 2 on the surface (press surface) of the quartz glass substrate 1 as a mask. (Cr mask 23). The Cr mask 23 is formed in an array with a pitch equal to or less than the operating wavelength. Next, as shown in FIG. 2 (f), the quartz glass substrate 1 on which the cylindrical Cr mask 23 is formed is placed in an RF dry etching apparatus, and the quartz glass substrate 1 is used using CHF ₃ + O ₂ gas. The surface of was etched. Thereby, the Cr mask 23 is etched little by little together with the quartz glass substrate 1, and the width is reduced. Then, by etching until the Cr mask 23 is completely removed, a conical non-reflective structure 2 having a pitch of 0.15 μm and a height of 0.15 μm was formed on the surface (press surface) of the quartz glass substrate 1. The surface roughness after etching was small, and the surface roughness was almost equal to the polished surface. Finally, an Ir—Rh alloy film for surface protection is formed to a thickness of 0.05 μm on the surface (press surface) of the quartz glass substrate 1 on which the conical non-reflective structure 2 is formed by using a sputtering method. did. Thus, the anti-reflection structure molding die 3 was obtained.

  The lower mold 4 has the following structure. That is, as shown in FIG. 1, a surface in which a recess 4 a of 15 mm × 15 mm × 0.5 mm is formed in a central portion of a cemented carbide mainly composed of 20 mm × 20 mm × 5 mm WC, and the recess 4 a is formed. In this case, an Ir—Rh alloy film for surface protection is formed with a thickness of 0.5 μm by sputtering.

  Hereinafter, a method of manufacturing an optical element having a non-reflective structure using the non-reflective structure molding die 3 and the lower mold 4 having the above-described configuration will be described with reference to FIGS. . FIG. 3 is a process diagram illustrating a molding process of an optical element having a non-reflection structure, and FIG. 4 is a process chart illustrating a press molding method of the optical element having a non-reflection structure.

  As shown in FIG. 3A, first, the above-mentioned non-reflective structure molding die 3 is fixed as the upper die 6 to the upper head 5 of the molding machine covered with the chamber 15, and the upper die 6 is pressed. The temperature was raised to a predetermined temperature (here, 590 ° C.) together with the stage 8. The preheating stage 7 was also heated to 590 ° C. Then, using the above lower mold 4 as the lower mold 10, a 15 mm × 15 mm × 1.0 mm crown borosilicate glass (transition point (Tg): 501 ° C., yield point (At): 549 ° C.) An optical material 11 is placed on the lower die 10, and the lower die 10 on which the optical material 11 is placed is introduced into the molding machine through the mold inlet 12 of the chamber 15, and the preheating stage 7 set at 590 ° C. Heated for 3 minutes. Here, a release agent 16 containing fine particles of carbon (C) for release is applied to the surface of the optical material 11 (see FIG. 4A).

  Next, as shown in FIG.3 (b), the lower mold | type 10 with which the optical material 11 was mounted was conveyed from the preheating stage 7 to the press stage 8 similarly set to 590 degreeC. Next, the cylinder 13 was lowered, and the optical material 11 was pressed for 3 minutes at a pressure of 1000 N by the upper mold 6 that was also set to 590 ° C. and fixed to the upper head 5 (FIG. 4A). (See (b)). Then, by raising the cylinder 13 without cooling (at the same temperature), the upper die 6 is raised together with the upper head 5, and the upper die 6 is released from the press-molded optical material 11 (FIG. 4 (b) and (c)). Here, the reason why the upper mold 6 can be released from the press-molded optical material 11 without cooling (while maintaining a high temperature) is that the wettability with the optical material 11 is poor. In other words, oxides and metals cannot be released without cooling (while still at high temperature), but carbon (C) (or boron nitride (BN)) is very poor in wettability. The mold can be released without cooling (while still at high temperature). When the upper mold 6 is released from the press-molded optical material 11, the press-molded optical material 11 is placed on the lower mold 10.

  Next, as shown in FIG. 3C, the lower die 10 on which the press-molded optical material 11 is placed is conveyed from the press stage 8 to the cooling stage 9 set to 300 ° C., where it is cooled for 3 minutes. did.

  Finally, the optical material 11 press-molded together with the lower mold 10 is taken out from the mold outlet 14 of the chamber 15, and after removing the press-molded optical material 11 from the lower mold 10, the release agent 16 is removed. did. Thereby, an optical element 17 having a non-reflective structure was obtained (see FIG. 4C).

  According to the present embodiment, as described above, the upper mold 6 (non-reflective structure molding mold 3) can be released from the press-molded optical material 11 without cooling. 6 (non-reflective structure molding die 3) and press-molded optical material 11 are prevented from generating thermal stress due to the difference in thermal expansion coefficient, and the accuracy of the pattern transferred to optical material 11 is increased. be able to. As a result, it is possible to repeatedly mold the optical element 17 having a highly accurate non-reflective structure that does not cause pattern deviation over a large area. Further, according to the present embodiment, since the optical element 17 is manufactured by press molding using the non-reflective structure molding die 3, the optical element 17 having the non-reflective structure is molded with good reproducibility. Can do. As a result, mass productivity is dramatically improved, and production costs can be significantly reduced.

In this embodiment, quartz glass is used as a mold material having excellent high temperature strength, heat resistance, and less surface roughness due to dry etching. However, the mold material is not necessarily limited to quartz glass. For example, silicon, a Ni alloy, a cemented carbide formed with a SiO ₂ film or a Si film, or the like may be used as a mold material.

  In the present embodiment, a crown-type borosilicate glass is used as the optical material 11, but the optical material is not necessarily limited to the crown-type borosilicate glass. If it is. As multi-component glass, aluminosilicate glass, flint glass, phosphate glass and the like are used in addition to borosilicate glass, and acrylic, Teflon (registered trademark of DuPont), polyethylene, polyolefin and the like are used as resin. Since the non-reflective structure is formed by molding, even if multi-component glass or resin is used as the optical material 11, an optical element having a non-reflective structure with a large aspect ratio can be obtained.

  In this embodiment, an Ir—Rh alloy film is used as a thin film for surface protection, but the thin film for surface protection is not necessarily limited to an Ir—Rh alloy film. The thin film for surface protection should contain at least one metal selected from the group consisting of Pt, Pd, Ir, Rh, Os, Ru, Re, W and Ta. If the release agent 16 is not evenly applied to the surface of the optical material 11, if there is no thin film for protecting the surface, the optical material 11 partially contacts the mold directly and is completely welded. It becomes impossible to release the mold at all. Then, if the mold is forcibly released, the optical material 11 is broken. A thin film for surface protection such as an Ir—Rh alloy film is for preventing this.

  In the present embodiment, a columnar Cr mask corresponding to the non-reflective structure 2 is formed on the surface (press surface) of the quartz glass substrate 1, but this is not necessarily limited to this configuration. It is not a thing. For example, the mask may be formed using a material such as Ni, Au, or C, or a polygonal columnar mask may be formed.

  In this embodiment mode, the resist is patterned into a columnar shape or a polygonal column shape by using electron beam lithography. However, the resist is formed into a circular shape by using X-ray lithography or photolithography using interference exposure. Patterning may be performed in a columnar shape or a polygonal columnar shape.

  In this embodiment mode, the mask is formed in a columnar shape or a polygonal columnar shape by wet etching. However, the mask may be formed in a columnar shape or a polygonal columnar shape by dry etching. .

[Second Embodiment]
In the present embodiment, the press molding die for the optical element having the non-reflective structure is substantially the same as that in the first embodiment (see FIG. 1). The press-molding mold according to the present embodiment is different from the press-molding mold according to the first embodiment in the following points. That is, in the present embodiment, when the anti-reflection structure molding die 3 is manufactured, the surface (press surface) of the quartz glass substrate 1 on which the conical anti-reflection structure 2 is formed is protected for the surface. Instead of forming the Ir—Rh alloy film, a carbon (C) film for mold release was formed to a thickness of 0.05 μm. For this reason, in the present embodiment, unlike the first embodiment, a mold release agent for mold release is not applied to the surface of the optical material 11 to be press-molded.

  The method of manufacturing the optical element 17 having the non-reflective structure using the non-reflective structure molding die 3 and the lower mold 4 is the same as that in the first embodiment (FIGS. 3 and 4), description thereof is omitted here.

  Also in this embodiment, for the same reason as in the first embodiment, the upper die 6 (non-reflective structure molding die 3) can be released from the press-molded optical material 11 without cooling. Therefore, the optical element 17 having a highly accurate non-reflective structure that does not cause a pattern shift over a large area can be repeatedly formed.

  In the present embodiment, when the non-reflective structure molding die 3 is produced, carbon for mold release is formed on the surface (press surface) of the quartz glass substrate 1 on which the conical non-reflective structure 2 is formed. (C) A film is formed, but the thin film for releasing is not limited to the carbon (C) film, and may be, for example, a boron nitride (BN) film.

[Third Embodiment]
In the present embodiment, the same press-molding mold as that of the first embodiment is used as the press-molding die for the optical element 17 having a non-reflective structure (see FIG. 1).

In addition, the molding process of the optical element 17 having a non-reflective structure in the present embodiment is substantially the same as that in the first embodiment. The molding process of the present embodiment is different from the molding process of the first embodiment in the following points. That is, in the present embodiment, the optical element 17 having a non-reflective structure is molded while introducing N ₂ and CO ₂ (10 vol.%) From the atmospheric gas inlet 18 of the chamber 15 into the molding machine. .

  When the optical element 17 having a non-reflective structure was molded in the above atmosphere, even after 10000 shot molding, there was no pattern deviation over the entire 15 mm × 15 mm region of the optical material 11, so that there was no high precision. It was found that the optical element 17 having a reflective structure can be repeatedly molded.

As a comparative example, when the optical element 17 having the non-reflective structure was molded under the same conditions while introducing only N ₂ gas into the molding machine, the upper mold 6 (non-reflective structure molding die 3). The releasability between the optical material 11 and the optical material 11 is poor, and after pressing the optical material 11, the upper die 6 (non-reflective structure molding die 3) is press-molded without being cooled (at the same temperature (590 ° C.)). It was not possible to release from the optical material 11. In this case, when the temperature is lowered to 400 ° C., the upper mold 6 is released from the press-molded optical material 11. After cooling by the cooling stage 9, the optical element 17 having a non-reflective structure is taken out. The surface was observed. As a result, an optical element pattern having a non-reflective structure is precisely formed in the center portion, but the pattern shift increases as the distance from the center increases, and the optical element pattern having a non-reflective structure is doubled near the outer periphery. It was. When the upper mold 6 (non-reflective structure molding die 3) is cooled after pressing the optical material 11, the upper mold 6 (non-reflective structure molding die 3) is separated from the press-molded optical material 11. In the method of manufacturing an optical element that cannot be molded, thermal stress is generated due to the difference in thermal expansion coefficient between the upper mold 6 (nonreflective structure molding die 3) and the optical material 11 to be press-molded. This is considered to be because the upper mold 6 (non-reflective structure molding mold 3) is displaced from the optical material 11. Therefore, with such a manufacturing method, it is difficult to repeatedly mold an optical element having a highly accurate non-reflective structure that does not cause pattern deviation over a large area.

On the other hand, when N ₂ and CO ₂ (10 vol.%) Are introduced into the molding machine as in the present embodiment, the upper mold 6 (non-reflective structure molding) remains at the temperature at which press molding is performed. It is possible to easily release the mold 3) from the press-molded optical material 11. Here, the upper mold 6 can be released from the press-molded optical material 11 without cooling (while maintaining a high temperature) because the CO ₂ gas is adsorbed on the surfaces of the optical material 11 and the mold. This is because the effect of the release agent and the release film can be exerted on the CO ₂ gas. As a result, generation of thermal stress due to the difference in thermal expansion coefficient between the upper die 6 (non-reflective structure molding die 3) and the optical material 11 to be press-molded is prevented and transferred to the optical material 11. Since the accuracy of the pattern can be increased, as described above, it is possible to repeatedly form the optical element 17 having a highly accurate non-reflective structure that does not cause pattern deviation over a large area.

In the present embodiment, the optical element 17 having a non-reflective structure is molded while introducing N ₂ and CO ₂ (10 vol.%) From the atmospheric gas inlet 18 of the chamber 15 into the molding machine. However, it is not necessarily limited to such an atmosphere, and a gas or mist containing carbon (C) or fluorine (F) in a constituent molecule in an inert gas such as nitrogen (N ₂ ) or argon (Ar) Any atmosphere may be used as long as the liquid is mixed. For example, the optical element 17 having a non-reflective structure is molded while introducing a mixed gas of N ₂ and CF ₄ (10 vol.%) Or a gas obtained by passing N ₂ gas into an ethylene glycol solution into the molding machine. Even if it goes, the effect similar to the above can be acquired.

[Fourth Embodiment]
In the present embodiment, the case where a plano-convex lens having a conical microstructure with a pitch of 0.15 μm and a depth of 0.15 μm on one surface which is a convex surface is described as an optical element having a non-reflective structure of the present invention. To do.

  In the present embodiment, a mold manufactured as follows was used as a non-reflective structure molding mold (upper mold). FIG. 5 is a process diagram schematically showing a method for producing a non-reflective structure molding die used in the fourth embodiment of the present invention.

As shown in FIG. 5A, first, the surface (press surface) of a cylindrical quartz glass substrate 25 having a thickness of 10 mm and a diameter of 5 mm, which is a press molding die for an optical element having a non-reflective structure, is made high. After processing into a concave curved surface that is the inverted shape of a convex lens by precision grinding and polishing, the surface (press surface) of the quartz glass substrate 25 processed into a concave curved surface is used for X-ray lithography using a spin coat method. A PMMA resist 26 as a resist was formed to a thickness of 0.5 μm. Next, as shown in FIGS. 5A and 5B, the X-ray lithography mask 28 is moved with high accuracy while irradiating the X-rays 27, so that the surface (press surface) of the quartz glass substrate 25 is As a mask 29 corresponding to the non-reflective structure, a conical pattern made of PMMA resist having a diameter of 0.15 μm and a height of 0.3 μm was formed at a pitch of 0.15 μm. The mask 29 is formed in an array with a pitch equal to or less than the operating wavelength. Next, as shown in FIGS. 5B and 5C, the quartz glass substrate 25 on which the mask 29 made of PMMA resist is formed is put into an RF dry etching apparatus, and CHF ₃ + O ₂ gas is used. The surface of the quartz glass substrate 25 was etched. Thereby, a conical non-reflective structure 30 having a pitch of 0.15 μm and a height of 0.15 μm was formed on the surface (press surface) of the quartz glass substrate 25. Finally, an Ir—Rh alloy film for surface protection is added to the surface (pressed surface) of the quartz glass substrate 25 on which the conical non-reflective structure 30 is formed by sputtering using a Cr film. It was formed with a thickness of 05 μm. Thus, a non-reflective structure molding die 31 was obtained.

  The lower mold has the following structure. That is, an Ir—Rh alloy film for surface protection is formed to a thickness of 0.5 μm on the surface of a cemented carbide mainly composed of columnar WC having a thickness of 10 mm and a diameter of 5 mm, using a sputtering method. ing.

  A method for manufacturing an optical element (plano-convex lens) having a non-reflective structure using a non-reflective structure molding die (upper die) 31 and a lower die is the same as that in the first embodiment. Therefore, the description is omitted here (see FIGS. 3 and 4).

  Also in the present embodiment, for the same reason as in the first embodiment, it is possible to release the upper mold (non-reflective structure molding die 31) from the press-molded optical material 11 without cooling. Therefore, it is possible to repeatedly mold an optical element (plano-convex lens) having a highly accurate non-reflective structure that does not cause pattern deviation over a large area.

  In this embodiment, the conical mask 29 corresponding to the non-reflective structure is formed on the surface (press surface) of the quartz glass substrate 25. However, the present invention is not limited to this configuration. Instead, for example, a polygonal pyramid mask may be formed.

Sectional drawing which shows the metal mold | die for press molding of the optical element which has a non-reflective structure Process drawing showing the fabrication process of non-reflective structure mold Process drawing showing molding process of optical element having non-reflective structure Process drawing showing press molding method of optical element having non-reflective structure Process drawing showing another manufacturing process of non-reflective structure mold

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,25 Quartz glass substrate 2,30 Nonreflective structure 3,31 Mold for nonreflective structure 4 Lower mold 5 Upper head 6 Upper mold 7 Preheating stage 8 Press stage 9 Cooling stage 10 Lower mold 11 Optical material 12 Mold Input port 13 Cylinder 14 Mold outlet 15 Chamber 16 Release agent 17 Optical element 18 Atmospheric gas inlet 20 Cr film 21, 26 PMMA resist 22 Cylindrical pattern 23 Cr mask 27 X-ray 28 X-ray lithography mask 29 Mask

Claims (13)

A mask corresponding to the non-reflective structure is formed on a mold material having excellent high temperature strength, heat resistance, and less surface roughness due to dry etching, and the non-reflective structure is formed on the surface of the mold material by dry etching. After forming, a thin film for surface protection is formed on the surface of the mold material, and a non-reflective structure molding mold is manufactured,
From the optical material obtained by press-molding an optical material coated with a release agent for mold release using the non-reflective structure molding die, and press-molding the non-reflective structure molding die without cooling Let mold release,
A method of manufacturing an optical element having a non-reflective structure in which the release agent is removed after the press-molded optical material is cooled. A mask corresponding to the non-reflective structure is formed on a mold material having excellent high temperature strength, heat resistance, and less surface roughness due to dry etching, and the non-reflective structure is formed on the surface of the mold material by dry etching. After the formation, a carbon (C) film or a boron nitride (BN) film is formed on the surface of the mold material as a thin film for mold release to produce a non-reflective structure molding mold,
Using the non-reflective structure molding die, press-molding an optical material, releasing the non-reflective structure molding die from the optical material that has been press-molded without cooling,
A method for producing an optical element having a non-reflective structure for cooling the optical material formed by press molding. A mask corresponding to the non-reflective structure is formed on a mold material having excellent high temperature strength, heat resistance, and less surface roughness due to dry etching, and the non-reflective structure is formed on the surface of the mold material by dry etching. After forming, a thin film for surface protection is formed on the surface of the mold material, and a non-reflective structure molding mold is manufactured,
Using the non-reflective structure molding die, an optical material is pressed in an atmosphere in which an inert gas is mixed with a gas or mist-like liquid containing carbon (C) or fluorine (F) in a constituent molecule. Molding, releasing the non-reflective structure molding die from the optical material press-molded without cooling,
A method for producing an optical element having a non-reflective structure for cooling the optical material formed by press molding. According to the mold material, quartz glass, silicon, Ni alloy, and any one of claims 1 to 3, which is one selected from the group consisting of those forming the SiO ₂ film or Si film on cemented carbide The manufacturing method of the optical element which has a non-reflective structure. The method for producing an optical element having an antireflective structure according to any one of claims 1 to 3, wherein the optical material is multi-component glass or resin. The material of the mask corresponding to the nonreflective structure is one selected from the group consisting of Cr, Ni, Au, and C. Manufacturing of an optical element having a nonreflective structure according to any one of claims 1 to 3. Method. The non-reflective structure according to any one of claims 1 to 3, wherein the mask corresponding to the non-reflective structure is a cylindrical or polygonal mask, and is formed in an array with a pitch equal to or less than a use wavelength. The manufacturing method of the optical element which has. A resist is formed on the mask corresponding to the non-reflective structure, and the resist is formed into a columnar shape or a polygonal column shape by electron beam lithography, X-ray lithography, or photolithography using interference exposure, and has a pitch equal to or less than a use wavelength. 4. The method according to claim 1, wherein the mask is formed in an array shape at a pitch of a use wavelength or less, by patterning in an array shape by wet etching or dry etching. A method for manufacturing an optical element having a reflective structure. The antireflective structure according to claim 1 or 3, wherein the thin film for surface protection contains at least one metal selected from the group consisting of Pt, Pd, Ir, Rh, Os, Ru, Re, W, and Ta. The manufacturing method of the optical element which has these. The method for producing an optical element having an antireflective structure according to any one of claims 1 to 3, wherein a material of the mask corresponding to the antireflective structure is a resist for X-ray lithography. The mask corresponding to the non-reflective structure is a conical or polygonal pyramid-shaped mask, and is formed in an array shape at a pitch equal to or less than a use wavelength by X-ray lithography. The manufacturing method of the optical element which has the non-reflective structure of description. The method of manufacturing an optical element having an antireflective structure according to claim 10 or 11, wherein a surface shape of the antireflective structure molding die is a curved surface. The optical element which has the non-reflective structure manufactured by the method in any one of Claims 1-12.

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