JP2004358559A - Method of manufacturing article with fine surface structure, and die and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily increase the height of a three-dimensional structure. <P>SOLUTION: A mold-releasing treated recessed die 20a is set on the lower side, and acrylic resin is applied thereon as ultraviolet curing resin 30. A projecting substrate 10a of a prestructural material subjected to silane coupling treatment beforehand in another process is pressed thereon, and the ultraviolet curing resin 30 which becomes excessive in shape transfer is removed from a substrate peripheral part. The ultraviolet curing resin layer 30 is cured by irradiating uniform ultraviolet rays, and after separating the die 20a, the transfer shape of the resin 30 is transferred to a quartz material 10a by a dry etching method to acquire a final product. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the manufacture and processing of products that exhibit an optical function, a mechanical function, or a physical function by performing fine processing on a surface. Such microfabrication is used for manufacturing optical elements such as MLA (micro lens array), diffractive optical element, deflecting optical element, refractive optical element, birefringent optical element, optical fiber optical element, beam splitter and the like. It is particularly suitable for use in manufacturing an optical element having an outer dimension of 10 mm or less. In addition, this method can be applied and used in a wide range of industrial fields such as micromachining, surface treatment methods for mechanical sliding parts (automotive engines, air conditioner compressors, etc.).
[0002]
[Prior art]
A) As a method of manufacturing a multilevel element using a lithography technique, N = 2 in (M−1) processes using M masks. ^M A method for manufacturing an element having a level step-like phase distribution has been proposed (see Non-Patent Document 1).
[0003]
B) A method in which a direct writing method using an electron beam, a laser beam, an ion boom, or the like, a method combining optical lithography, and a dry etching technique has been proposed (see Non-Patent Document 2).
[0004]
C) Producing a target three-dimensional structure on a photosensitive material layer by a concentration distribution mask method and transferring the shape to a final product material by dry etching has been proposed (see Patent Document 1). The density distribution mask is a mask having a transmittance distribution not only in an in-plane pattern but also in a film thickness direction.
[0005]
D) Proposing a mold in advance and transferring this shape to the surface of the product material by resin transfer, and transferring the resin shape after the transfer to the final product material by dry etching have been proposed (see Patent Document 2). ).
[0006]
[Non-patent document 1]
"Optical Technology Contact," Vol. 38, no. 5 (2000) p. 42-51, especially P.I. 45
[Non-patent document 2]
Applied Physics, Vol. 68, No. 6, (1999); 633-638
[Patent Document 1]
JP 2001-356470A
[Patent Document 2]
JP-A-2002-192500
[0007]
[Problems to be solved by the invention]
The method A requires that a large number of masks be required, that the number of alignments is so large that the error cannot be ignored, that the etching error in the depth direction cannot be ignored, that the minimum line width is limited to about 1 μm, and the like. It is a problem.
[0008]
In the method B, a device having a high-precision control technique is required, the device is expensive, drawing takes a very long time (about 10 to 15 hours for a 500 μm × 500 μm square), and there is no mass productivity. , Poor reproducibility, etc., and there are no practical examples.
[0009]
With respect to the problem of producing a highly accurate surface three-dimensional structure with good reproducibility, the above methods C and D can achieve the problem well. In addition, the method D of transferring using a mold also has an advantage of reducing the manufacturing cost.
[0010]
An object of the present invention is to improve the method of the above D, and to make it easy to increase the height of the three-dimensional structure. Increasing the height of the three-dimensional structure means increasing the numerical aperture (NA) of an optical lens to make the lens brighter.
The present invention also aims to extend the life of the mold.
[0011]
[Means for Solving the Problems]
The present invention is a method for producing an article having a convex or concave microstructure on the surface, comprising the following steps (A) to (F).
(A) a step of fabricating a pre-structure having a structure in which the size of the fine structure as the final target is reduced on the surface as a final product material;
(B) a step of subjecting the surface of a mold having a fine shape having a size substantially corresponding to the final target fine structure and having a fine shape in which concavities and convexities are inverted to the fine structure to a surface of a mold,
(C) pressing the final product material to the mold via a curable resin between the surface of the mold subjected to the mold release treatment and the surface of the final product material in which the pre-structure is manufactured; A step of transferring an inverted shape of the mold surface shape to the resin,
(D) a step of curing the resin after the transfer in the step (C),
(E) removing the resin from the mold with the resin cured in step (D) bonded to a final product material; and
(F) transferring the shape transferred to the resin present on the final product material after the step (E) to the final product material by a dry etching method, wherein the pre-structure has a size of a final target structure; The process of transferring under the dry etching condition which is enlarged.
[0012]
There are various methods for manufacturing a fine shape on a target substrate, but when manufacturing by a dry etching method, the higher the height of the target shape is, the more difficult it is to manufacture. The reason for this is that the higher the height, the greater the amount of etching, the longer the processing time, and the more difficult it becomes to make a high-precision shape in exponential proportion to the processing time. Therefore, in the present invention, a pre-structure having a fine shape having a structure substantially similar to a target shape is manufactured in advance, and the processing time of dry etching is relatively shortened.
[0013]
In addition, there are various methods for manufacturing a mold. However, the higher the height of a target shape is, the more difficult it is to manufacture. Therefore, in the present invention, a metal mold having a fine shape having a structure substantially similar to a desired shape is manufactured. Then, by setting conditions so that the height is increased in a subsequent transfer step by dry etching, the height of the shape of the final target structure becomes higher than the shape of the mold.
[0014]
The mold used for transferring to the resin in the present invention also includes an intermediate mold formed by transferring a resin from a base mold.
In the present invention, since the surface of the mold or the intermediate mold is subjected to the mold release treatment, the resin is easily separated from the mold or the intermediate mold. This also extends the life of the mold and the intermediate mold, and improves transferability.
Further, the pre-structure and the die are aligned with a mark called a registration mark for alignment provided in advance in the initial stage, and manufactured so that the optical axes are aligned.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The pre-structure does not require the fine structure accuracy compared to the final product. Therefore, it can be formed by various methods. An example of the method is as follows. (1) Sand blast method, (2) Dry etching method, (3) Wet etching method, (4) Dicing method, (5) Grinding method, (6) Cutting method, (7) Film forming method (vacuum deposition, sputtering, (8) sol-gel method, (9) glass bonding method and the like. Among them, the sandblast method and the wet etching method will be described in detail in Examples. The dry etching method is a method of forming a pre-shape on a substrate surface by lithography and dry etching. The dicing method, the grinding method, and the cutting method are methods for mechanically processing the substrate surface to form a pre-shape. The film formation method is a method in which a mask is arranged at a position away from the substrate to form a convex pre-form on the substrate. The sol-gel method uses a tetraalkyl orthosilicate, applies a solution prepared by hydrolysis and polycondensation to a pre-shaped pattern, removes the solvent by drying, and performs a heat treatment to complete the siloxane bond. This is a method of forming a pre-shape from silica glass. The glass bonding method is to bond a pattern surface of a glass substrate on which a pattern is separately formed to a final target substrate surface with an HF solution or water, leave it in a vacuum, and then bond by heating at 250 ° C. for 10 minutes or more, Thereafter, the bonded glass substrate is polished from the back side to expose a pattern, thereby forming a pre-shape by the pattern.
As the resin for transferring the inverted shape of the surface shape of the mold, an ultraviolet curable resin or a thermosetting resin can be used.
[0016]
The use of an ultraviolet curable resin as the transfer resin has the following advantages.
(1) Curing at room temperature is possible.
(2) Since it can be applied in liquid form, it has good fluidity and can prevent the generation of bubbles and the like.
{Circle around (3)} Since the curing can be performed by uniformly irradiating the ultraviolet light, the curing can be performed uniformly.
(4) Can be cured in a short time.
{Circle over (5)} Many ultraviolet curable resins have been developed with a small amount of shrinkage, and the range of adoption is wide.
(6) High degree of freedom in “molecular design with plasma resistance”.
[0017]
As a result, the use of the ultraviolet curable resin makes it possible to transfer the surface shape of the mold more accurately and easily.
Further, even when a thermosetting resin is used as the transfer resin, the surface shape of a mold or an intermediate mold can be accurately transferred as in the case of the ultraviolet-curable resin by curing uniformly. As the thermosetting resin, a resin used for manufacturing a plastic spectacle lens or a contact lens can be used. A molding method using such a thermosetting resin is called a casting method, in which a liquid thermosetting resin is poured into a mold, gradually heated, and cured for about 24 hours. .
[0018]
With respect to mold production, if the fine shape of the mold surface is larger than 1 mm, it can be processed by high-precision machining (NC lathe, NC ultra-precision machining machine, etc.) which is usually commercially available.
If the fine shape of the mold surface is 1 mm or less, it can be manufactured by the method proposed by the inventors (see Patent Document 1), or lithography and wet processing of a glass or metal material. It can also be manufactured by etching.
[0019]
If the fine shape of the mold surface is extremely fine, such as 10 μm or less, the resist (photosensitive) formed on the mold base material by the method already proposed by the inventors (see Patent Document 2). A desired shape with an electron beam (EB) or a laser beam on a conductive material) and develop it to form a fine structure, and then transfer the fine structure to a mold base material by dry etching. is there.
[0020]
The method includes the following steps (a) to (c).
(A) a step of applying a photosensitive material on a mold base material surface,
(B) exposing the photosensitive material using a concentration distribution mask, and then developing to form a desired shape on the photosensitive material;
(C) a step of transferring the shape of the photosensitive material to the mold base material by a dry etching method.
In this way, if the shape of the resist is transferred to the mold base material by the dry etching method, the shape of the resist, which is a soft material, can be transferred to the hard mold material.
[0021]
Although the mold used in the present invention includes an intermediate mold, the intermediate mold can be manufactured by including the following steps (a) to (e).
(A) a step of subjecting the surface of another base mold to a release treatment;
(B) pressing the mold base material against the mold via a curable resin between the surface of the mold subjected to the mold release treatment and the surface of the mold base material, and the surface of the mold; Transferring the inverted shape of the shape to the resin,
(C) a step of curing the resin after the transfer in the step (b),
(D) removing the resin from the mold while the resin cured in step (c) is joined to the mold base material; and
(E) a step of transferring the shape transferred to the resin present on the mold base material after the step (d) to the mold base material by a dry etching method.
[0022]
When a mold is manufactured by a dry etching method, the mold base material needs to be a material that can be dry-etched, such as a metal material, a glass material, a ceramic material, a plastic material, and a hard rubber material. Can be used.
[0023]
When using an ultraviolet-curing resin as the curing resin and irradiating the resin with ultraviolet rays through a mold, the material for forming the mold is a heat-resistant, ultraviolet-curing resin such as synthetic quartz or heat-resistant glass. Those having a property of transmitting light at a wavelength for curing the resin are preferable. Pyrex (registered trademark), Neoceram (registered trademark), or the like can be used as the heat-resistant glass.
[0024]
When manufacturing a mold, the selectivity is changed stepwise or continuously in order to transfer a desired shape in a dry etching process in a process of transferring a shape of a photosensitive material to a mold base material by a dry etching method. Preferably. Thus, by changing the selection ratio stepwise or continuously, a desired shape can be obtained at the time of transfer.
[0025]
An example of the mold release treatment of the mold surface is to form a metal thin film on the surface of a mold or an intermediate mold, and the metal thin film is formed of Ni, Cr, Fe, Al, Co, Cu, Mo, Pt, It can be made of a single metal such as Au, Nb, Ti or a composite material. By this mold release treatment, the shape transferability of the mold is remarkably increased, and accurate transfer can be performed, and at the same time, the releasability is facilitated and the life of the mold and the intermediate mold is drastically improved.
[0026]
As the release treatment, it is preferable to further perform a surface treatment on the metal thin film with a layer containing a finely structured fluororesin. This surface treatment can be performed by forming a layer containing a fluorine resin by a plating method or a vapor deposition method.
As another release treatment method for the mold surface, a method of forming an organic compound layer having a fluorine functional group on the surface of a mold or an intermediate mold is also preferable.
[0027]
When an ultraviolet-curable resin is used as the resin for transferring the inverted shape of the mold surface shape, at least one of the mold and the final product material is used as a method of curing the ultraviolet-curable resin. Use a material that is light transmissive to light in a wavelength range that can cure the material. Then, in the curing step of the ultraviolet-curable resin, when only one material is a light-transmitting material, it passes through the light-transmitting material, and when both materials are light-transmitting materials, one or both of the materials are light-transmitting materials. It is preferable that the UV-curable resin is irradiated with light through a light-transmitting material so that the UV-curable resin is uniformly cured. By uniformly curing the ultraviolet curing resin, the shape transferability of the mold is dramatically increased, and accurate transfer can be performed.
[0028]
When a thermosetting resin is used as the resin to transfer the inverted shape of the mold surface shape, as a method of curing the thermosetting resin, the mold and the final product material are fixed while being positioned, and the resin injection port is set. Separately provided, a thermosetting resin is injected between the mold and the final product material from the resin injection port. In the curing step of the thermosetting resin, it is preferable to heat and cure the resin while gradually heating so that the heat is uniformly distributed to the entire mold and the final product material sandwiching the thermosetting resin.
[0029]
Generally, the resin shrinks upon curing. Therefore, it is preferable that the amount of shrinkage of the resin is determined in advance, and in the process of manufacturing a mold for transferring the shape to the resin, the shape of the mold is corrected so as to be deeper in consideration of the amount of shrinkage. This makes it possible to correct the curing shrinkage amount.
[0030]
When pressing the final product material through the resin on the surface of the mold that has been subjected to the mold release treatment, a silane coupling agent treatment or the like to improve the adhesion between the resin and the surface of the final product material. It is preferable to perform primer surface treatment. Thereby, in the peeling step, the peeling is selectively performed from the mold side, and the resin cracking (a part of the resin remains in the mold at the time of peeling) is sharply reduced.
[0031]
As a result, shape transferability in the next step is improved. When the final product material is pressed against the surface of the mold via a resin, it is important to provide a gap (space) between the surface of the mold and the final product material. This gap can be used as a flow path for supplying the amount of contraction when the resin cures from the surroundings. As a method, the mold has a plurality of convex portions that form a flow path for supplying a volume decrease due to the shrinkage of the resin from the surrounding resin to a material surface that is opposed to and bonded to the mold. Is preferably formed around the periphery.
[0032]
When transferring the shape transferred to the resin to the final product material by dry etching, the etching selectivity between the resin and the final product material in the dry etching is stepwise or stepwise in order to form a desired shape in the final product material. Preferably, it is changed continuously. By adjusting the selection ratio, the shape can be corrected, and the image can be transferred to a desired shape.
[0033]
In the transfer to the final product material, the maximum thickness of the resin layer is transferred to the final product material. Since the pre-structure is formed in the final product material, the maximum thickness of the resin layer is smaller than the height of the unevenness of the final product material, and the etching time required for that is short.
[0034]
【Example】
(Example 1)
The opposing fiber-coupled optical element 2 shown in FIG. 1 was manufactured. The coupling optical element 2 has a diameter Φ formed on both sides of a synthetic quartz material. ₀ Is about 0.784mm, height H ₀ Is a 40 μm lens, which is a concentrically arranged aspherical shape. (A) shows a state in which the coupling optical element 2 is arranged on the light source side, and the coupling optical element 2 condenses and receives light from the optical fiber 4a. (B) shows a state in which the coupling optical element 2 is arranged on the light receiving side, and the light received by the coupling optical element 2 is condensed and guided to the optical fiber 4b. Reference numerals 6a and 6b denote quartz flat plates disposed at the tips of the optical fibers 4a and 4b, respectively.
[0035]
The final target structure of the optical element for optical communication is a lens having a diameter of 0.784 μm formed of 210 pieces (= 15 × 14) on both sides of a synthetic quartz material. The radius of curvature is 1.8897 mm and the height is 40.0 μm.
This coupling optical element 2 is formed as a microlens array 8 as shown in FIG. 2A is a plan view, and FIG. 2B is a cross-sectional view taken along the line XX. The microlens array 8 has an effective lens number of 12 rows × 13 columns = 156 and a lens arrangement pitch P of 1.1 mm. Note that the outermost lens is only disposed as an optical performance adjusting lens and is not actually used.
[0036]
Next, a manufacturing procedure of this optical element will be described.
First, a pre-shape was manufactured.
FIG. 3 shows a step of forming a resist pattern for producing a pre-shape.
An exposure mask for shielding a portion corresponding to the lens arrangement in FIG. 2 from light is prepared in advance. The diameter of the light shielding portion of the mask prepared here is substantially the same as the shape of the final target lens.
[0037]
(A) A 200 nm thick Cr metal film is formed on a quartz substrate 10 by a sputtering method. Further, a photosensitive resist material (OFPR-5000-500, manufactured by Tokyo Ohka) 14 is uniformly coated on the Cr metal film with a thickness of 5 μm by a spin coater, and pre-baked (130 ° C. × 100 seconds).
[0038]
(B) Thereafter, after exposure with the above-mentioned mask, development and rinsing were performed, post-baking (150 ° C. × 60 minutes) was performed in an oven to form a resist pattern 14.
Then, using the resist pattern 14 as a mask, the Cr metal film 12 was etched with a wet etching solution to remove portions other than the resist portion. At this time, the cross section of the Cr metal film 12 is obliquely etched by an undercut during wet etching.
[0039]
FIG. 4 shows a step of forming a pre-shape by a sandblast method.
(A) On a quartz substrate 10 on which the resist pattern 14 and the Cr metal film pattern 12 are formed as described above, a sandblasting material having a particle size (mesh # 500) is applied with air pressure from above vertically using a commercially available sandblasting device. Spray while using.
[0040]
(B) As a result, the quartz substrate material 10 is gradually scraped together with the sandblast material by a physical impact. However, (1) collision occurs between the blast material entering vertically from above and the “blast material and quartz powder” removed from below upward. Due to this phenomenon, a phenomenon occurs in which the tip of the convex portion 11 becomes narrower (narrower) as it is dug deeper. Also, (2) the resist material 14 on the upper surface of the substrate 10 is gradually removed because it cannot withstand the impact of the sandblast material. Similarly, the Cr metal film 12 is also gradually removed. Since the cross section of the Cr metal film 12 is obliquely etched by an undercut during wet etching, the method of sandblasting also proceeds obliquely, and a slope appears so that the taper is increased. In the pre-shape formed by the above method, the tip of the projection 11 has a flat surface with a diameter of 0.2 mm, and the base has a diameter Φ ₁ Is about 0.76mm, height H ₁ Was able to obtain a quartz substrate 10a having a convex array shape having a roughly spherical shape of about 30 μm. The convex portion 11 has a diameter Φ of the final objective lens. ₀ , Height H ₀ The size is smaller than that of.
The pre-structure manufactured by the sand blast method cannot be used optically as it is because the surface is rough.
[0041]
The mold was manufactured in the manner shown in FIG.
In this embodiment, a concave mold is used. A neoceram mold was manufactured and used as the concave mold. The outline of the manufacturing procedure is shown below.
First, the product was manufactured in the following procedure.
(1) Target height: A convex mold having a height of 20.5 / 40.0 of 40.0 μm (a reduced structure of 0.5125 times, that is, n = 1.951) is manufactured on a silicon substrate. It was to be.
[0042]
A silicon substrate having a diameter of 6 inches and a thickness of 0.625 mm was prepared as the mold base material 20. A photosensitive material (resist) (TGMR-950, manufactured by Tokyo Ohka Co., Ltd.) was applied on the surface of the mold base material 20 by a spinner at 1000 rpm. At this time, the resist film thickness was 25.0 μm. Next, prebaking was performed on a hot plate at 100 ° C. for a baking time of 180 seconds.
[0043]
Next, a concentration distribution mask prepared in advance (designed so as to have a target structure and a height of 20.5 μm. The resist thickness after coating is exposed and developed. Irradiation of 2,000 mJ was carried out with a stepper using a film thinner at a portion which was not formed.
When transferring the shape to the silicon substrate, the selectivity is set to 1.2. After the shape was transferred to the silicon substrate, the height became 24.6 μm.
[0044]
(2) Next, after transferring the shape to the silicon substrate, the mold is transferred to a separately prepared neoceram intermediate material to obtain a concave intermediate mold. At this time, the selectivity at the time of dry etching was transferred to 1.4 (here, since the shrinkage ratio of the resin was 4%, the height of the silicon mold of 24.6 μm was transferred to the resin to 24.6 μm). × 0.96 = 23.6 μm, which is transferred to the neoceram intermediate material with a selectivity of 1.4, so that the height after the transfer is 23.6 μm × 1.4 = 33.0 μm.) The shape at this time is inverted and concave.
[0045]
(3) Finally, the intermediate mold shape is transferred to a quartz material which is a final product material. At this time, the selectivity at the time of dry etching was transferred at 1.29 (here, since the shrinkage ratio of the resin was 4%, the height of the neoceram intermediate mold of 33.0 μm was transferred to the resin to 33.0 μm. × 0.96 = 31.7 μm, which is transferred to the final product material with a selectivity of 1.29, so that the height after the transfer is 31.7 μm × 1.29 = 40.9 μm.) The shape at this time is forward and convex (the middle mold is inverted).
[0046]
The manufacturing procedure of this optical element will be described in more detail with reference to FIGS. 6 and 7A to 7H. FIGS. 6 and 7 show an example in which two independent lenses are manufactured for simplification of description, but the situation is exactly the same when manufacturing 156 lenses.
(A) A silicon substrate having a diameter of 6 inches and a thickness of 0.625 mm was prepared as a mold base material 411. A Cr film 414 is formed on the mold base material 411 to a thickness of 800 ° by a sputtering method, and the Cr film around the region where the target optical lens is formed is partially formed along the circle by photolithography and etching. For example, six points are formed along the outer circumference of the circle.
[0047]
This portion 415 serves as a spacer for the resin flow path in the step of transferring the shape from the intermediate mold to the final product material. That is, this portion 415 is in a convex state higher than the surroundings, corresponding to the spacer convex portion 455 in the drawing of the step (E) described later.
[0048]
A photosensitive material (resist) (TGMR-950, manufactured by Tokyo Ohka Co., Ltd.) was applied on the surface of the mold base material 411 having the Cr film 414 by a spinner. At this time, the resist film thickness was 25.0 μm. Next, prebaking was performed at 100 ° C. for a baking time of 180 seconds.
[0049]
Next, 2,000 mJ irradiation was performed with a stepper using a concentration distribution mask (having a target structure and designed in advance so as to have a height of 20.5 μm).
Thereafter, after development and rinsing, UV hardening treatment was performed to form resist patterns 412 and 413. FIG. 6A shows this state. Reference numeral 413 denotes a resist pattern for a spacer for securing a resin flow path in the step of transferring the shape from the silicon mold to the intermediate mold. The height of the target optical element resist pattern 412 (reduced to 1 / n) is about 0.2 μm lower than the resist pattern 413 for the flow path securing spacer.
[0050]
(B) Next, the resist patterns 412 and 413 and the Cr film pattern 414 were transferred to the mold base material 411 by a dry etching method. The dry etching at this time uses a TCP (inductively coupled plasma) etching apparatus, ₃ : 5.0 sccm, CF ₄ While introducing gas of 10.0 sccm, substrate bias voltage: 500 W, upper electrode power: 1250 W, vacuum degree 1.5 × 10 5 ^-3 Etching was performed at Torr (that is, 1.5 mTorr) for 21 minutes. At this time, the etching rate was 0.8 μm / min. The process was terminated by slightly over-etching. The etching selectivity (etching rate of silicon as a mold base material / etching rate of resist) is 1.4, and the height of the optical lens portion 422 after etching is 28.7 μm (= 20.5 × 1.4). )Met. The surface roughness was good when Ra = 0.001 μm or less. This shape height does not allow for shrinkage of the resin in the next step. Here, in order to secure a resin flow path in the next step, a convex spacer 423 is formed in a silicon mold 411a on the outer peripheral side of the optical lens portion 422 during mask exposure, and a sufficient resin flow path is formed. This is because they have been secured.
[0051]
Reference numeral 425 denotes a concave portion formed in the silicon mold 411a, and corresponds to the portion 415 from which the Cr film has been removed in the step (A). The concave portion 425 is located at the lowest point, and the selectivity of (silicon / Cr film) is higher than the selectivity of (silicon / resist). It is deeply etched to a depth of about 0.2 μm.
[0052]
At this time, the shape of the optical lens portion 422 of the silicon mold 411a was similar to the shape of the resist pattern 412 after exposure.
In order to release the surface of the silicon mold 411a, a triazine thiol organic compound having a fluorine functional group was formed to a thickness of 1000 ° and surface-treated as in Example 1.
[0053]
(C) Next, the silicon mold 411a subjected to the mold release treatment is set so that the surface on which the optical lens portion 422 is formed faces upward, and an acrylic resin 434 (Dainippon Ink Co., Ltd.) is applied thereon as an ultraviolet curable resin. Co., Ltd .: 3 g of GRANDIC RC-8720).
[0054]
This silicon mold 411a was set in a special bonding machine, and a silane coupling treatment (adhesion improving treatment) was performed in another step in advance, and a plate-like intermediate material 431 (manufactured by Nippon Sheet Glass: Neoceram (registered trademark)) was used. Press the plane slowly. At this time, bonding was performed by an automatic bonding machine whose descending speed was controlled so that bubbles were not generated in the ultraviolet-curable resin 434.
[0055]
Next, the resin was slowly pushed up from the silicon mold 411a side to the intermediate material 431 side, and the ultraviolet curable resin 434 that became unnecessary at the time of shape transfer was removed from the outer peripheral portion of the substrate. Further, the ultraviolet curable resin layer 434 was cured by irradiating 4000 mJ of uniform ultraviolet light from the back surface side of the intermediate material 431. Ultraviolet irradiation was performed from the center of the optical element. At this time, the resin 434 contracts in volume, but the intermediate material 431 is pressed by the spacer 423 (preventing the resin 434 from lowering downward), so that the surrounding resin moves to compensate for the volume decrease due to the resin contraction. . Therefore, there is no contraction in volume and no difference in height. The thickness of the ultraviolet-curable resin layer 434 after curing was 0.1 μm or less. The maximum thickness of the ultraviolet curable resin layer 434 is “pattern depth 28.7” + “top layer interval 0.1” = 28.8 μm.
[0056]
(D) Next, in order to peel off the ultraviolet-curable resin layer 434 from the surface of the silicon mold 411a while keeping the ultraviolet-curable resin layer 434 bonded to the intermediate material 431, a silicon substrate (silicon mold 411a) having a low rigidity is slightly applied using a jig. Peeling was performed while deforming to a convex shape. When the silicon mold 411a is peeled off from the resin 434, the surface shape of the silicon mold 411a is inverted and transferred to the resin 434 remaining on the intermediate material 431. The optical lens portion 422 of the silicon mold is a concave portion 442, and the concave portion 425 of the silicon mold is a convex portion 445 for a spacer.
[0057]
When the transfer shape of the resin layer 434 on the surface of the intermediate material 431 was measured, the depth (concave shape) of the optical element portion 442 was reduced to 27.6 μm. This is because the resin layer 434 cured and shrunk (here, since the shrinkage of the resin is 4%, it is 28.7 μm × 0.96 = 27.6 μm).
[0058]
(E) Next, the shape of the resin layer 434 on the intermediate material 431 was transferred to the intermediate material 431 by dry etching in the same manner as described above. Dry etching conditions were as follows: using a TCP etching apparatus, CHF ₃ : 15.0 sccm, CF ₄ : 15.0 sccm, Ar: 10.0 sccm while introducing gas, substrate bias voltage: 500 W, upper electrode power: 1250 W, degree of vacuum 1.5 × 10 ^-3 Etching was performed at Torr (that is, 1.5 mTorr) for 51 minutes. At this time, the etching rate was 0.80 μm / min.
[0059]
CHF in the second half of etching ₃ Etching was performed with the gas amount increased by 4.0 sccm and the selectivity slightly increased. By changing the selection ratio stepwise, a desired shape could be obtained at the time of transfer. The etching selectivity was 1.5 on average, and the height of the shape after etching was 40.0 μm. The surface roughness was good when Ra = 0.001 μm or less.
[0060]
As a result, an intermediate mold 431a having the lens concave portion 452 and the spacer convex portion 455 for securing the resin flow path in the next shape transfer step was obtained. At this time, the shape of the intermediate mold 431a had a constant pitch and only the height was 1.95 times (40.0 μm / 20.5 μm) as compared with the silicon mold 411a.
[0061]
In order to release the surface of the intermediate mold 431a, the surface of the intermediate mold 431a was treated with a triazinethiol organic compound having a fluorine functional group. This was performed by a method called an organic plating method. Specifically, a fluorinated organic thin film was formed on the surface of the intermediate mold 431a by performing an electrolytic polymerization treatment in a solution obtained by dissolving a compound having an -OH group at the terminal of the fluorinated SFTT in a solvent. Under these conditions, a film was formed at a thickness of 1000 °. Neoceram and quartz of the intermediate mold 431a are both made of SiO. ₂ Therefore, it is possible to cope with the same release processing.
[0062]
(F) Next, the release mold-processed intermediate mold 431a is placed so that the surface having the shape thereof faces upward, and an acrylic resin (GRANDIC RC manufactured by Dainippon Ink Co., Ltd.) is formed thereon as an ultraviolet curable resin 464. -8720) was applied in an amount of 3 cc. The ultraviolet curable resin 464 is applied more to the lens part.
[0063]
The intermediate mold 431a is set in a special bonding machine, and a final structure is formed from a resin on which a pre-structure is formed as described with reference to FIG. 3 and a silane coupling process (adhesion improving process) is performed in another process. A quartz material substrate (synthetic quartz manufactured by Shin-Etsu Quartz Co., Ltd.) 461 for the product is slowly pressed. At this time, bonding was performed by an automatic bonding machine whose descending speed was controlled so that bubbles were not generated in the ultraviolet curable resin 464. Thus, the ultraviolet curing resin 464 is sandwiched between the intermediate mold 431a and the plane substrate 461.
[0064]
Next, the resin was slowly pushed up from the intermediate mold 431a side to the final product material (quartz) 461 side, and the ultraviolet curable resin 464 which became unnecessary during the shape transfer was removed from the outer peripheral portion of the substrate.
Next, 3000 mJ of uniform ultraviolet light was irradiated from the back side of the final product material 461 to cure the ultraviolet curable resin layer 464. Also in this case, ultraviolet irradiation is performed from the center of the optical element. At this time, the volume of the resin 464 shrinks, but since the final product material 461 is pressed by the spacer 455 (preventing the resin 464 from lowering downward), the resin 464 moves so as to compensate for the volume decrease due to the resin shrinkage. (The spacer 455 seems to seal the resin in the figure, but the spacer 455 is formed only partially and the resin is movable. Therefore, the volume shrinks and the height decreases. There is no difference.
The thickness (portion other than the optical element portion) of the cured ultraviolet-curable resin layer 464 was 0.1 μm or less. The maximum thickness of the ultraviolet curable resin layer 464 is “pattern depth 38.4” + “top layer interval 0.1” = 38.5 μm.
[0065]
(G) Next, in order to peel off the ultraviolet-curable resin layer 464 from the surface of the intermediate mold 431a while being bonded to the final product material 461, the layer was peeled using a jig.
When the shape of the resin layer 464 on the surface of the final product material 461 was measured, the height (convex shape) of the optical element portion was reduced to 9.8 μm.
[0066]
(H) Next, the shape of the resin layer 464 on the final product material 461 was transferred to the final product material 461 by dry etching in the same manner as described above. Dry etching conditions were as follows: using a TCP etching apparatus, CHF ₃ 10.0 sccm, CF ₄ : 24 sccm, Ar: 5.0 sccm while introducing gas, substrate bias voltage: 500 W, upper electrode power: 1250 W, vacuum degree 1.5 × 10 5 ^-3 Etching was performed at Torr (ie, 1.5 mTorr) for 13.5 minutes. The etching rate at this time was 0.78 μm / min.
[0067]
In the latter half of the etching, an automatic pressure controller (APC) was used to continuously lower the total pressure from 3 mTorr to 1.0 mTorr to increase the selectivity over time, thereby performing etching. By changing the selection ratio stepwise, a desired shape could be obtained at the time of transfer. The etching selectivity was 1.04 on average, and the height of the shape after etching was 40.0 μm. The surface roughness was good when Ra = 0.001 μm or less.
[0068]
Thus, the optical element 2 shown in FIGS. 1 and 2 is formed on one side of the substrate.
After the optical element 2 on one surface is formed, the optical element 2 on the other surface is formed on the other surface of the substrate in the same manner as described above, with the formed optical element 2 protected by a jig or a mask. The optical element 2 is thus formed.
At this time, the positioning of the optical elements 2 on both sides is performed based on a positioning mark provided in advance.
[0069]
(Example 2)
In the same manner as in Example 1, the opposed fiber coupling element shown in FIGS.
[0070]
In this example, the pre-shape was manufactured by the method of FIG. Hereinafter, a method of manufacturing a pre-shape will be described first.
(A) An exposure mask is prepared in advance to shield a portion corresponding to the lens arrangement in FIG. The diameter of the light shielding portion of the mask prepared here is substantially the same as the target shape of the final target lens shape.
[0071]
A photosensitive resist material (OFPR-5000-500, manufactured by Tokyo Ohka) 14 is uniformly applied to the quartz substrate 10 with a thickness of 5 μm by a spin coater, and pre-baked under a predetermined condition (130 ° C. × 100 seconds on a hot plate). did.
Then, after exposure using the above mask, development and rinsing were performed to form a resist pattern 14, and post-baking was performed in an oven (150 ° C. × 60 minutes).
Next, the quartz substrate 10 is fixed to a dedicated jig. The purpose of this fixing is (1) for etching with a dedicated device and (2) for protecting the back surface of the quartz substrate 10.
[0072]
(B) Next, the quartz substrate 10 was wet-etched with an etching (HF) liquid using a dedicated wet-etching device to etch portions other than the resist portion 14. In this wet etching apparatus, the quartz substrate 10 is rotated by a rotating mechanism, and (2) the concentration of the etchant is controlled to a constant concentration, and is sprayed from a nozzle having a sufficient flow rate.
[0073]
The pre-shaped substrate 10a is obtained by this etching, and the cross section of the etched portion of the pre-shaped substrate 10a is sufficiently stirred with the slope formed by the undercut by etching as shown in FIG. 9B. And a flat surface of the bottom surface.
[0074]
The pre-shaped substrate 10a formed by the above method has a flat surface having a flat surface with a diameter of 0.2 mm at the front end and a roughly spherical shape with a base end of about 0.5 mm in diameter and about 30 μm in height. A convex array was obtained. However, as compared with the pre-structure manufactured by the sand blasting method of the first embodiment, the pre-structure is deviated from the target shape by the amount of undercut. Further, since the surface is rough, it cannot be used optically as it is.
The same mold as that used in Example 1 was used.
[0075]
The final manufacturing procedure of the optical element was performed by the procedure shown in FIG.
(A) As the UV-curable resin 30, 3 cc of an acrylic resin (GRANDIC RC-8720, manufactured by Dainippon Ink) was applied in the same manner as in Example 1.
[0076]
(B) In the curing step of the UV-curable resin 30, similarly to the first embodiment, UV curing is performed by irradiating uniform ultraviolet light from the back side of the quartz material 10a with 3000 mJ (300 seconds × 10 mW) over 5 minutes. The mold resin layer 30 was cured.
The thickness at the top position of the three-dimensional structure of the UV-curable resin layer 30 after curing, that is, the distance between the top of the three-dimensional structure of the UV-curable resin layer 30 and the quartz material 10a was about 10 μm. At this time, the thickness of the ultraviolet-curable resin layer 30 on the slope of the three-dimensional structure, that is, the distance between the slope of the three-dimensional structure of the ultraviolet-curable resin layer 30 and the projection of the quartz material 10a is about 12 at the maximum. .2 μm. Therefore, the thickest part of the ultraviolet curable resin layer 30 is the slope part (about 12 μm) of the pre-structured quartz material 10a.
[0077]
(C) Next, in order to peel off the ultraviolet curable resin layer 30 from the surface of the mold 20a while being bonded to the quartz material 10a, the jig is used to deform the low-rigidity silicon mold 20a into a slightly convex shape. And peeled off.
Next, when the transfer shape of the resin layer 30 on the quartz material surface was measured, the height (convex shape) of the optical element portion was reduced to 11.60 μm. This is because the resin layer 30 was cured and shrunk, and the curing shrinkage was about 5% on average. The contraction rate could be reduced by irradiating slowly and for a long time. The height at this time is accurately measured by an optical (non-contact) shape measuring instrument, and the selection ratio and the etching conditions (change of the selection ratio over time) in the subsequent step (d) are appropriately set. is important. However, compared to Example 1, the amount of deviation from the target shape was increased due to the shrinkage of the resin on the slope portion.
[0078]
(D) Next, the transferred shape of the resin 30 on the quartz material 10a was transferred to the quartz material 10a by a dry etching method in the same manner as in Example 1 to obtain a final product. The dry etching conditions were as follows using a TCP etching apparatus and CHF ₃ : 12.0sccm, CF ₄ : Substrate bias voltage: 500 W, upper electrode power: 1250 W, vacuum degree: 1.0 × 10 while introducing gas of 4 sccm ^-3 Etching was performed at Torr (that is, 1.0 mTorr) for 30.0 minutes. At this time, the etching was performed at a depth of 13 μm and an etching rate of 0.43 μm / min.
[0079]
CHF in the second half of etching ₃ Etching was performed by increasing the gas amount by 2.0 sccm and slightly increasing the selectivity. By changing the selection ratio in four steps, a desired shape could be obtained at the time of transfer. The etching selectivity (etching rate of quartz material / etching rate of resin layer) was 1.05 on average, and the height of the surface shape of the final product after etching was 40.0 μm. The surface roughness (Ra) was good when Ra = 0.001 μm or less. Note that the optical surface had an aspherical shape.
[0080]
At this time, the shape of the final product had a constant pitch and only a height of 1.05 times the shape after resin transfer. The target shape was achieved.
As in Example 1, the above steps were repeated on both surfaces of the substrate 10 to form optical elements, thereby obtaining the final products shown in FIGS.
[0081]
(Example 3)
Hereinafter, a final manufacturing procedure of the optical element will be described with reference to FIG.
As a pre-shape manufacturing method, rough processing was performed using a dry etching method, and a rough shape was first manufactured. As the schematic shape, a mask in which a density distribution mask was designed in advance for this embodiment was used. Specifically, a photosensitive material (resist: TGMR-950, manufactured by Tokyo Ohka Co., Ltd.) was applied in a thickness of 25 μm, exposed using the above mask, developed, and rinsed. After post-baking, processing was performed by dry etching with the average selectivity set at 1.47. Thus, the shape was transferred to the quartz substrate, which is the final product material. The final height at this time was about 30.1 μm.
[0082]
The pre-shaped substrate 10a manufactured by the above method and the mold 20a manufactured in the first embodiment are used.
(A) The concave mold 20a having been subjected to the mold release treatment was set below, and 3 cc of an acrylic resin (GRANDIC RC-8720, manufactured by Dainippon Ink Co., Ltd.) was applied as a UV-curable resin 30 thereon.
[0083]
(B) The mold 20a is set in a special bonding machine, and a convex substrate (manufactured by Shin-Etsu Quartz Co., Ltd.) of a pre-structured material (final product material) that has been subjected to a silane coupling treatment (adhesion improving treatment) in another step in advance : Synthetic quartz) 10a is pressed slowly from above. At this time, bonding was performed by an automatic bonding machine whose descending speed was controlled so that bubbles were not generated in the ultraviolet curable resin 30. Further, on the surfaces of the quartz substrate 10a for pre-structure fabrication and the silicon mold 20a, register mark patterns having shapes opposite to each other are formed by a metal film. When the substrate 10a is pressed from above, alignment is performed while checking the register mark pattern, and the substrate 10a is slowly lowered.
Next, the resin was slowly pushed up from the mold 20a side to the quartz material 10a side, and extra UV-curable resin 30 which was unnecessary at the time of shape transfer was removed from the outer peripheral portion of the substrate.
[0084]
Next, uniform ultraviolet light was irradiated from the back side of the quartz material 10a to 3000 mJ (300 seconds × 10 mW) for 5 minutes to cure the ultraviolet-curable resin layer 30. At this time, the thickness at the top position of the three-dimensional structure of the ultraviolet-curable resin layer 30, that is, the distance between the top of the three-dimensional structure of the ultraviolet-curable resin layer 30 and the quartz material 10a was about 10 μm. At this time, the thickness of the ultraviolet-curable resin layer 30 on the slope of the three-dimensional structure, that is, the distance between the slope of the three-dimensional structure of the ultraviolet-curable resin layer 30 and the projection of the quartz material 10a is about 9 at maximum. 0.0 μm. Therefore, the thickest part of the ultraviolet curable resin layer 30 is the top part (about 10 μm) of the pre-structured quartz material 10a.
[0085]
(C) Next, in order to peel off the ultraviolet curable resin layer 30 from the surface of the mold 20a while being bonded to the quartz material 10a, the jig is used to deform the low-rigidity silicon mold 20a into a slightly convex shape. And peeled off.
Next, when the transfer shape of the resin layer 30 on the surface of the quartz material 10a was measured, the height (convex shape) of the optical element portion was reduced to 9.60 μm. This is because the resin layer 30 was cured and shrunk, and the curing shrinkage was about 4% on average. The contraction rate could be reduced by irradiating slowly and for a long time. The height at this time is accurately measured by an optical (non-contact) shape measuring instrument, and the dry etching selectivity and the etching conditions (change of the selectivity over time) in the subsequent step (a) are appropriately set. It is important to.
[0086]
(D) Next, the transferred shape of the resin 30 on the quartz material 10a was transferred to the quartz material by a dry etching method to obtain a final product. The dry etching conditions were as follows using a TCP etching apparatus and CHF ₃ : 12.0sccm, CF ₄ : Substrate bias voltage: 500 W, upper electrode power: 1250 W, vacuum degree: 1.0 × 10 while introducing gas of 4 sccm ^-3 Etching was performed at Torr (that is, 1.0 mTorr) for 25.0 minutes. At this time, the etching was performed at a depth of 11 μm and an etching rate of 0.44 μm / min.
[0087]
In the latter half of the etching, the etching was performed using an APC apparatus while continuously reducing the total pressure from 3 mTorr to 1.0 mTorr and increasing it with time. By changing the selection ratio in three steps, a desired shape could be obtained at the time of transfer. The etching selectivity (etching rate of the quartz material 10a / etching rate of the resin layer 30) was 1.05 on average, and the height of the surface shape of the final product after etching was 40.0 μm. The surface roughness (Ra) was good when Ra = 0.001 μm or less. Note that the optical surface had an aspherical shape.
At this time, the shape of the final product had a constant pitch and only a height of 1.05 times the shape after transfer to the resin 30. The target shape was achieved.
[0088]
Thus, the optical element 2 shown in FIGS. 1 and 2 is formed on one side of the substrate.
After the optical element 2 on one surface is formed, the optical element 2 on the other surface is formed on the other surface of the substrate in the same manner as described above, with the formed optical element 2 protected by a jig or a mask. The optical element 2 is thus formed.
At this time, the positioning of the optical elements 2 on both sides is performed based on a positioning mark provided in advance.
[0089]
【The invention's effect】
In the present invention, the surface of a mold having a fine shape on the surface is subjected to a mold release treatment, and the final material is pressed against the mold surface with a pre-structure via a curable resin, thereby forming the surface shape of the mold. The inverted shape is transferred to the resin, the resin is cured, and the shape is transferred to the final product material by dry etching to manufacture an article with a fine surface structure. By forming and taking care of it, it becomes easy to increase the height of the fine structure in the dry etching process, and the fine structure (high-precision surface three-dimensional structure) having the desired height can be mass-produced with high precision. It has become possible.
In addition, by performing the mold release treatment on the mold, the life of the mold can be further extended.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part showing an example of an optical element manufactured according to the present invention, wherein (A) shows a light source side and (B) shows a light receiving side.
FIG. 2A is a plan view of the optical element, and FIG. 2B is a cross-sectional view taken along the line XX.
FIG. 3 is a process cross-sectional view illustrating a photolithography process for forming a pre-structure in one embodiment.
FIG. 4 is a process cross-sectional view showing a sand blast process for forming a pre-structure in the same example.
FIG. 5 is a process sectional view showing a process of forming a mold in the example.
FIG. 6 is a process flow sectional view showing a first half of the example.
FIG. 7 is a process flow sectional view showing the latter half of the example.
FIG. 8 is a process sectional view showing a process of manufacturing a final product in the example.
FIG. 9 is a process cross-sectional view showing a wet etching process for forming a pre-structure in another embodiment.
[Explanation of symbols]
2 Opposed fiber coupling optical element
8 Micro lens array
10 Quartz substrate
10a Pre-structured substrate
12 Cr metal film
14,22 Photosensitive resist material
20 Mold base material
20a mold
30,434,464 UV curable resin
411 Mold base material (silicon substrate)
431a Intermediate mold

Claims (13)

A method for producing an article having a convex or concave microstructure on the surface, comprising the following steps (A) to (F).
(A) a step of fabricating a pre-structure having a structure in which the size of the fine structure as the final target is reduced on the surface as a final product material;
(B) a step of subjecting the surface of a mold having a fine shape having a size substantially corresponding to the final target fine structure and having a fine shape in which concavities and convexities are inverted to the fine structure to a surface of a mold,
(C) pressing the final product material to the mold via a curable resin between the surface of the mold subjected to the mold release treatment and the surface of the final product material in which the pre-structure is manufactured; A step of transferring an inverted shape of the mold surface shape to the resin,
(D) a step of curing the resin after the transfer in the step (C),
(E) removing the resin from the mold in a state where the resin cured in step (D) is bonded to a final product material, and (F) on the final product material after the step (E). Transferring the shape transferred to the resin existing in the above to the final product material by a dry etching method, wherein the step of transferring the pre-structure under dry etching conditions to enlarge the size of the pre-structure to the size of the final target structure. The method according to claim 1, wherein the transferring step (F) transfers the maximum thickness of the resin layer to a final product material. 3. The method according to claim 1, wherein the transferring step of the step (F) includes changing a dry etching condition to change a selectivity. 4. 4. The method according to claim 3, wherein the change in the selectivity includes a change over time. 5. The curable resin is a UV-curable resin, one or both of the final product material and the mold are a UV-permeable material, and the curing step of the step (D) includes UV irradiation. The production method according to any one of the above. The manufacturing method according to any one of claims 1 to 5, wherein the mold has the fine shape formed by lithography and dry etching on a surface of a mold base material that can be dry-etched. The manufacturing method according to claim 6, wherein the mold has a mold base material that is a flat substrate and the fine shape is formed on a planar surface thereof. The amount of shrinkage when the resin is cured is determined in advance,
When transferring a fine shape to a final product material by dry etching in the transferring step of the step (F), dry etching conditions are set so that the fine shape is corrected to be formed deeper in consideration of the amount of shrinkage. 8. The production method according to any one of 1 to 7. 2. A primer surface treatment for improving adhesion between a resin and a surface of the final product material when the final product material is pressed against the mold surface via a resin in the step (C). 9. The production method according to any one of items 1 to 8. The manufacturing method according to any one of claims 1 to 9, wherein the production of the pre-structure in the step (A) is any of the following methods.
(1) Sand blast method, (2) Dry etching method, (3) Wet etching method, (4) Dicing method, (5) Grinding method, (6) Cutting method, (7) Film forming method (vacuum deposition, sputtering, (8) sol-gel method, and (9) glass bonding method. A method for manufacturing a transfer mold including the following steps (a) to (c).
(A) a step of applying a photosensitive material on a mold base material surface,
(B) exposing the photosensitive material using a concentration distribution mask and then developing to form a desired shape on the photosensitive material; and (c) forming the shape of the photosensitive material by a dry etching method. The process of transferring to a mold base material. A method for manufacturing a transfer mold including the following steps (a) to (e).
(A) a step of performing a mold release treatment on the surface of another mold;
(B) pressing the mold base material against the mold via a curable resin between the surface of the mold subjected to the mold release treatment and the surface of the mold base material, and the surface of the mold; Transferring the inverted shape of the shape to the resin,
(C) a step of curing the resin after the transfer in the step (b),
(D) removing the resin from the mold while the resin cured in step (c) is bonded to the mold base material; and (e) removing the resin from the mold after the step (d). Transferring the shape transferred to the resin present on the base material to the mold base material by a dry etching method. It has a size almost matching the final target microstructure, has a fine shape in which the fine structure is inverted from the fine structure on the surface, and is bonded to the surface of the final product material via a curable resin. Mold
A mold having a convex portion for forming a flow path for supplying a volume decrease accompanying shrinkage when the resin is cured from surrounding resin.

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