JP2003156614A - Method for forming pattern, optical parts and method for manufacturing optical parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a fine pattern with a high aspect in a plastic material consisting of a UV-curing resin, to provide optical parts having the pattern and to provide a method for manufacturing the parts. SOLUTION: The method for forming a pattern includes steps of: forming a photosensitive resin pattern on a substrate; forming a UV-curing resin layer on the photosensitive resin pattern in a tight contact state; transferring the photosensitive resin pattern to the UV-curing resin layer; irradiating the UV- curing resin layer with UV rays to harden the resin; and then releasing the UV-curing resin layer from the substrate. The optical parts have UV-curing resin layers having patterns formed by the above method for forming a pattern as the optical structural material.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a pattern forming method,
More specifically, the present invention relates to an optical component and a method for manufacturing the optical component, more specifically, a method for forming a fine pattern such as a diffractive optical element typified by a diffraction grating or a Fresnel zone plate, an optical component including the fine pattern, and an optical element. It relates to a manufacturing method of parts.

[0002]

2. Description of the Related Art An optical component represented by a diffraction grating and a Fresnel zone plate is one in which a regular fine pattern is formed on the surface of an optical film having a specific refractive index, and it depends on what kind of pattern is produced. , A lens, a multiplexing / demultiplexing wave, a wavelength filter, etc. can be provided. For example, the diffraction grating is a set of straight line patterns having a constant width, and the Fresnel zone plate is a set of concentric circle patterns in which the line width gradually narrows as the radius increases.

Two methods are known for producing such a diffractive optical element, one of which is a method using a machine tool called a ruling engine. The ruling engine is a carving machine that attaches a tool to a precision stage to make a reciprocating motion, and feeds a substrate placed on the stage at predetermined intervals to make a groove. At the beginning of the ruling engine development, it was difficult to perform microfabrication because the substrate feed depended on the precision of the feed screw, but recently, the optical wave interferometer and servo technology that enable accurate measurement of the stage position on the spot. With the development of, it has become possible to process grating grooves on the submicron level.

Another method of manufacturing a diffractive optical element is a method using a lithography technique and a dry etching technique, which have made remarkable progress in recent semiconductor integrated circuit manufacturing. As the lithography technology, "holographic exposure method" that uses the interference of two light beams of a laser, and "electron beam drawing method" that uses an electron beam focused to a small diameter
Is used, a photosensitive resin pattern is formed on the substrate by these methods, and the substrate is dry-etched using the photosensitive resin pattern as a mask to form a lattice groove.

It is possible to directly process the optical glass to obtain a diffractive optical element by any method using such a ruling engine or lithography, but recently, a mold is produced by using these methods. Then, a method of mass-producing diffractive optical elements by injection-molding plastic is used. Here, the mold is an original plate in which the irregularities of the pattern of the diffractive optical element are reversed, and is made of a hard metal that can withstand the high temperature during injection molding, such as Ni or stainless steel.

FIG. 5 is a diagram for explaining the principle of injection molding. First, the mold 51 shown in FIG.
As shown in FIG. 5B, the plastic material 52 melted at a high temperature is poured into the mold 51 through the injection member 53, and finally, as shown in FIG. With the method of releasing the mold 51 from the mold 51 to obtain the plastic 54 having a desired shape, it has become possible to manufacture a highly accurate mold by the progress of the ruling engine and the lithography technique, and by the progress of the injection molding technique, the precision is high. This is a method widely used in bar code reader reading mechanism parts, compact disc pickup mechanism parts, and the like, because the duplicated products can be manufactured at low cost. Further, recently, a plastic material having stable optical characteristics has been developed, and its use is expanding more and more.

[0007]

In recent years, as the application area of optical parts provided with a fine pattern has expanded, the fine pattern has come to have a high degree of optical function. For this reason, the demands on the pattern shape and quality are becoming stricter. For example, the accuracy of a lattice pattern having a line width of 200 nm or less or a groove pattern having a depth of several μm is 10 nm.
It is required to be suppressed below, or groove pattern processing with an aspect ratio (ratio of height and width) of 10 or more is required.

However, it is very difficult to manufacture a die having such a fine pattern with a large aspect ratio by machining such as a ruling engine, and
There is also a problem that a technique for controlling the temperature of the substrate and the environment with high precision is required to obtain a highly precise fine pattern.

On the other hand, according to the method using the lithography technique and the dry etching technique, a fine pattern having a width of 100 nm or less and an aspect ratio of 10 can be formed, and it is possible to manufacture a highly accurate mold, but an aspect ratio is used. Even if a mold with a fine pattern with a large ratio is obtained, it is difficult to reliably embed the plastic material melted in the injection molding process into the fine pattern of the mold, and if the aspect ratio is large, Since the plastic material is destroyed at the time of mold release, it is not easy to manufacture a highly accurate plastic part by injection molding. In injection molding, usually, a technique of forming a material that is easy to release on the surface of a mold is often used, but in a mold having a fine pattern as described above, the size and the depth change depending on the thickness of the material. Therefore, the coating cannot be formed on the surface, and the stable formation by injection molding is generally limited to patterns having a width of 200 nm or more and an aspect ratio of about ½.

The present invention has been made in view of the above problems, and an object thereof is to use a lithography technique and an ultraviolet curable resin without using a mold at all for producing a fine and high aspect ratio plastic material. It is an object of the present invention to provide a method for forming a fine pattern, a high-performance optical component provided with such a pattern, and a method for manufacturing the same.

[0011]

In order to achieve such an object, the present invention provides a method for forming a pattern of an ultraviolet curable resin layer, wherein the invention is a photosensitive resin on a substrate. A first step of forming a pattern of, and a second step of forming a pattern of the photosensitive resin by closely adhering an ultraviolet curable resin layer on the pattern of the photosensitive resin, and transferring the pattern of the photosensitive resin to the ultraviolet curable resin layer, It is characterized by at least including a third step of irradiating the ultraviolet-ray-cured resin layer that has been pattern-transferred with ultraviolet rays to cure the layer, and a fourth step of peeling the cured ultraviolet-ray-curable resin layer from the substrate.

The invention according to claim 2 is an optical component comprising a pattern-formed UV curable resin layer on an optical structure, wherein the UV curable resin layer is the pattern according to claim 1. It is characterized in that the pattern is formed by the forming method.

Further, the invention according to claim 3 is a method for producing an optical component comprising a pattern-formed ultraviolet curable resin layer on an optical structure, which is photosensitive on a substrate transparent or opaque to ultraviolet rays. A first step of forming a resin pattern,
A second step of forming a UV curable resin layer having an adhesive function in close contact with the photosensitive resin pattern and transferring the pattern of the photosensitive resin to the UV curable resin layer; and a step transparent or opaque to UV rays. A third step of adhering the optical structure onto the ultraviolet curable resin layer, a fourth step of irradiating the ultraviolet curable resin layer with ultraviolet rays to cure it, and peeling the cured ultraviolet curable resin layer from the substrate. At least one of the substrate and the optical structure is transparent to ultraviolet light, and the irradiation of ultraviolet light in the fourth step is performed on either the substrate or the optical structure transparent to ultraviolet light. It is characterized in that it is performed from one or both sides.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining a structural example of a pattern forming method of the present invention. First, as shown in FIG. 1A, a photosensitive resin 12 is formed on a Si wafer substrate 11 by using a lithography technique. Form a pattern. The substrate is not limited to the Si wafer, and any substrate having a smooth surface may be used.

Next, as shown in FIG. 1 (b), an ultraviolet curable resin 13 is applied on the pattern of the photosensitive resin 12 to a desired thickness, and further, as shown in FIG. 1 (c), the ultraviolet curable resin. After irradiating 13 with ultraviolet rays to cure it, as shown in FIG. 1D, a film of ultraviolet curing resin 13 is applied to the Si wafer substrate 1.
Peel from 1. Finally, if the photosensitive resin 12b attached to the film of the ultraviolet curable resin 13 is removed with a solvent such as acetone, a pattern having irregularities opposite to the pattern of the photosensitive resin 12 as shown in FIG. It is possible to form a film of the ultraviolet curable resin 13 having

The ultraviolet curable resin 13 used here is
Since it is a material that is widely used as an adhesive for optical fibers for optical communication and can be used sufficiently as a material for optical parts, and the refractive index control technology of this resin has already been developed, There is a merit that the UV-curable resin film with a pattern formed by the method shown in can be used as it is as an optical component.

FIG. 2 is a view for explaining another constitutional example of the pattern forming method of the present invention. The method shown in FIG. 1 is a method for producing an optical component by using an ultraviolet curable resin alone. On the other hand, this method is a method of preparing an optical structure such as glass in advance and forming an ultraviolet curable resin pattern on the surface of the optical structure.

First, as shown in FIG. 2A, a photosensitive resin 22 is formed on a Si wafer substrate 21 by using a lithography technique.
2B, the ultraviolet curable resin 23 is dropped on the pattern of the photosensitive resin 22 and the glass plate 24 is adhered thereon. Further, as shown in FIG. 2C, after the ultraviolet curable resin 23 is irradiated with ultraviolet rays to be cured, the film of the ultraviolet curable resin 23 is peeled from the Si wafer substrate 21 as shown in FIG. 2D. To do. Since the ultraviolet curable resin 23 has a function as an adhesive, it is firmly adhered to the glass plate 24. Finally, if the photosensitive resin 22b attached to the film of the ultraviolet curable resin 23 is removed with a solvent such as acetone, the pattern of the ultraviolet curable resin 23 can be easily formed on the surface of the glass plate 24 as shown in FIG. 2 (e). Can be formed into In the method shown in FIG. 2, if a lens is used instead of the glass plate 24, a compound lens in which a diffractive optical element and a refraction lens are combined can be formed according to the same method.

As described above, the pattern forming method of the present invention does not use a mold which can be repeatedly used as in the conventional injection molding, but allows the photosensitive resin pattern to play a role of the mold. To form one plastic pattern and then remove it. Therefore, the pattern forming method of the present invention does not cause a problem at the time of mold release in injection molding.

Further, although the ultraviolet curable resin used in the pattern forming method of the present invention has a limitation that it is not damaged by the solvent of the photosensitive resin, in general, the photosensitive resin is easily dissolved by acetone. On the other hand, many UV-curable resins are difficult to be dissolved by acetone, so if acetone is used as a solvent, only the photosensitive resin can be removed without damaging the UV-curable resin. Examples of the photosensitive resin having such characteristics include OF as an ultraviolet photosensitive resin.
PR-800 (Tokyo Ohka product name), electron beam and X
UVII (made by Shipley, trade name) as a photosensitive resin for wires
Etc.

Further, the ultraviolet curable resin can smoothly penetrate into the gap between the photosensitive resin patterns to transfer the shape as the photosensitive resin pattern is passed, and since heat from the outside is not required at the time of curing, Since the deformation caused by and the shrinkage rate at the time of curing are small, there is an advantage that a pattern faithfully reflecting the photosensitive resin pattern can be formed.

In the pattern forming method of the present invention, since the pattern formed on the ultraviolet curable resin faithfully reflects the pattern of the photosensitive resin, its accuracy depends on the pattern accuracy of the photosensitive resin. On the other hand, the accuracy of the photosensitive resin pattern does not depend on the lithography method for forming the pattern, and an optimum lithography method can be selected to obtain the required pattern accuracy. For example, if the pattern has a width of 0.2 μm or more, ultraviolet lithography can be used, and the width of 0.2
Electron beam lithography can be used for fine patterns of μm or less. Further, X-ray lithography is suitable for obtaining a fine pattern having a large aspect ratio.
A pattern with an m width and a pattern with an aspect ratio of 10 or more can be easily formed. It has been proved in the manufacture of semiconductor integrated circuits that a pattern with an accuracy of better than 5% can be formed by any of these lithography methods.

Since a technique capable of controlling the film thickness of the photosensitive resin with an accuracy of 10 nm has already been established, if the film thickness is too thick after the photosensitive resin pattern is formed, it is thinned using oxygen plasma or the like. It is also possible. Further, recently, a technique for changing the light blocking rate of a mask for ultraviolet lithography has been developed. By using this technique, a sawtooth-shaped or stepped photosensitive resin pattern can be formed.

As described above, by using the advanced lithographic technology in recent years, it is possible to form a fine photosensitive resin pattern having a sufficient accuracy to satisfy the shape required for the optical component. Also,
Since such a photosensitive resin pattern can be formed on the entire surface of an 8-inch wafer at a speed of 20 to 30 sheets per hour, there is no cost limitation considering that the size of the optical component is at most 10 mm.

In the pattern forming method shown in FIG.
Since an optical structure that is transparent to ultraviolet rays such as glass is used, it is possible to perform ultraviolet irradiation from above to cure the ultraviolet curable resin, but when the optical structure is not transparent to ultraviolet rays or is very large. Cannot irradiate ultraviolet rays from above to cure the resin. In this case,
It is possible to cure the resin by forming a photosensitive resin pattern on a UV transparent substrate such as a glass plate instead of the Si wafer, applying the UV curable resin, and then irradiating the UV from the back surface of the substrate. .

An example in which an optical component is manufactured by using the pattern forming method of the present invention described above will be described below.

(Example 1) OFPR-800, which is a positive photosensitive resin, was applied on a Si wafer having a diameter of 8 inches.
After coating to a thickness of 0 μm and baking at 80 ° C. for 30 minutes, a plurality of line patterns having a width of 0.8 μm were formed at intervals of 0.8 μm by using ultraviolet lithography. Since the photosensitive resin in this case is a positive type, most of the wafer surface is covered with the photosensitive resin. The post bake is 100 ° C, 2
It went for 0 minutes. When the pattern of the photosensitive resin thus formed was measured using a scanning electron microscope, the pattern width was 0.814 μm, and it had a substantially rectangular cross section.
Further, the film thickness was measured using a stylus type step gauge, and it was found to be 1.92 μm.

Next, two drops of an ultraviolet curable resin having a refractive index of 1.512 was dropped onto this photosensitive resin pattern with a dropper, and spread over an area having a diameter of 8 mm, and the central portion had a thickness of about 1 mm. It was In this state, ultraviolet rays were irradiated from the upper portion for 30 seconds to cure the ultraviolet curable resin. After that, when this wafer was immersed in acetone, the photosensitive resin layer was dissolved in acetone in about 20 seconds, and the ultraviolet curable resin could be peeled off. The UV curable resin peeled off in this way is a transparent plastic, no residue of the photosensitive resin is observed, the refractive index is 1.512, which is the same as the raw material, and the pattern formed on the surface is observed by a scanning electron microscope. As a result of observation, it has a substantially rectangular cross section and the pattern width is 0.810.
The pattern depth was 1.95 μm.

As described above, by using the pattern forming method of the present invention, a pattern extremely faithful to the photosensitive resin pattern can be formed on the plastic surface. In addition,
The substrate provided with this pattern can be used as it is as an optical component.

In this embodiment, the step of peeling the ultraviolet curable resin from the Si wafer and the step of removing the photosensitive resin adhering to the peeled ultraviolet curable resin are carried out at the same time. Peel off by other methods,
Similar results can be obtained by removing the photosensitive resin thereafter.

(Example 2) Diameter 8 inches and thickness 0.75
UVII, which is a positive type X-ray photosensitive resin, is applied to a thickness of 0.35 μm on a Si wafer having a size of 0.3 mm, baked at 120 ° C. for 120 minutes, and then has a width of 0.1 μm using X-ray lithography.
20 line patterns of m, 0.2 μm, 0.3 μm, and 0.5 μm were formed at the same intervals as the line width.
After X-ray exposure, baking was performed at 150 ° C. for 90 minutes, and after development, baking was performed at 100 ° C. for 60 minutes. Since the X-ray was exposed to light having a large transmittance with respect to the resin, the cross section of the formed pattern was an almost perfect rectangle, and the thickness thereof was 0.33 μm. Moreover, the pattern width of the photosensitive resin was measured by a scanning electron microscope.

Next, a refractive index of 1.512 is applied on this pattern.
After dropping one drop of the ultraviolet curable resin with a dropper, a glass plate having a thickness of 1 mm and a side of 100 mm and a refractive index of 1.512 was placed and held so that the ultraviolet curable resin had a uniform film thickness. In this state, UV rays are irradiated from the upper part for 30 seconds to cure the UV curable resin, and then this wafer is immersed in acetone. In about 20 seconds, the X-ray photosensitive resin dissolves in acetone, and the glass plate is covered with plastic. The ultraviolet curable resin was peeled off from the wafer with the resin attached.

No residue of the X-ray-sensitive resin was observed in the ultraviolet curable resin, and the pattern formed on the surface was observed with a scanning electron microscope. As a result, the pattern depth was 0.33 μm in a substantially rectangular cross section. It was The obtained pattern widths are as shown in Table 1, and the patterns substantially matched with the patterns formed on the photosensitive resin.

[0035]

[Table 1] (Unit: μm)

According to the results of this experiment, when the pattern forming method of the present invention is used, the aspect ratio is 3.3 with a width of 0.1 μm.
It has been revealed that the plastic pattern can be formed. Further, in another experiment in which the thickness of the photosensitive resin was 2.0 μm, it was confirmed that a pattern having a width of 0.2 μm and an aspect ratio of 10.0 could be formed.

As a result of measuring the optical transmittance of the glass plate to which the ultraviolet curable resin thus obtained was adhered, there was no reflection at the boundary because the refractive indices of the ultraviolet curable resin and the glass plate were matched. The transmittance was 99% or more.

(Example 3) Diameter 8 inches, thickness 0.75
After applying the photosensitive resin OFPR-800 to a thickness of 2.0 μm on a glass plate having a thickness of mm and baking at 80 ° C. for 30 minutes,
The pattern was formed using ultraviolet lithography.

FIG. 3 is a diagram for explaining the structure of the light-shielding rate changing type photomask used at this time and the photosensitive resin pattern. The light-shielding rate changing type photomask is a glass plate as shown in FIG. 3A. A photosensitive resin pattern obtained by forming a light-shielding film in which the light-shielding rate changes stepwise in a concentric region having a diameter of 100 μm on 31 is formed on a substrate 33 as shown in FIG. 3 (b). It was possible to form a diffractive lens having the formed concentric stepped photosensitive resin pattern 34 and the concentric stepped pattern. The post-baking was performed at 100 ° C. for 20 minutes.

FIG. 4 is a view for explaining the manner in which the ultraviolet curable resin pattern is formed at the tip of the optical fiber by using the photosensitive resin pattern thus formed. First, as explained in FIG. On the photosensitive resin pattern 42 formed on the glass plate 41 formed in step 1, one drop of the ultraviolet curable resin 43 having a refractive index of 1.5 is dropped with a dropper, and from there,
The diameter is 1 according to the center of the concentric circle of the photosensitive resin pattern 42.
The tip of the quartz optical fiber 44 of 00 μm is fixed. In this state, ultraviolet rays were irradiated from the back surface of the glass plate 41 for 30 seconds to cure the ultraviolet curable resin 43. Then, when the glass plate 41 was immersed in acetone, the photosensitive resin 42 was dissolved in acetone in about 20 seconds, and the ultraviolet curable resin 43
With the glass plate 4 bonded to the tip of the optical fiber 44.
1 was peeled off, and the ultraviolet curable resin 43 spread around the optical fiber 44 was removed. As a result of microscopic observation of the pattern formed at the tip of the optical fiber 44, a pattern almost as designed was obtained.

In this embodiment, the optical structure is an optical fiber, and it is difficult to irradiate the ultraviolet ray from the upper part of the optical fiber to cure the ultraviolet curable resin. It is formed on a transparent glass plate, and ultraviolet rays are irradiated from the back surface of the glass plate to cure the resin.

[0042]

As described above, the pattern forming method of the present invention is a method of forming a pattern of an ultraviolet curable resin using a photosensitive resin pattern formed by a lithography method as an original plate,
If only a photosensitive resin pattern can be formed, a pattern of an ultraviolet curable resin that faithfully transfers it can be formed. Therefore 0.1
It is also possible to form a pattern with a width of μm and an aspect ratio of 3 or more.

Further, since the photosensitive resin pattern can be formed on a flat and smooth substrate, which is completely different from the optical structure to be patterned, an extremely ideal photosensitive resin pattern can be formed. On the other hand, since the ultraviolet curable resin has a function as an adhesive, it can be patterned on the optical structure composed of almost all materials such as glass and Si. Therefore, as the optical structure, not only the lens and the fiber but also optical components having various other structures can be used.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a configuration example of a pattern forming method of the present invention.

FIG. 2 is a diagram for explaining another configuration example of the pattern forming method of the present invention.

FIG. 3 is a diagram for explaining a light blocking rate changing type photomask and a photosensitive resin pattern in the pattern forming method of the present invention.

FIG. 4 is a diagram for explaining a method for forming a pattern on the tip of an optical fiber by using the pattern forming method of the present invention.

FIG. 5 is a diagram for explaining the principle of injection molding.

[Explanation of symbols]

11, 21 Si wafer 12, 12a, 12b, 22, 22a, 22b Photosensitive resin 24, 31, 41 Glass plate 32 Light-shielding film 33 Substrate 34, 42 Photosensitive resin pattern 13, 23, 43 UV curable resin 44 Optical fiber 51 Mold 52 Plastic material 53 Injection member 54 Plastic of desired shape

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasunao Saito             2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo             Nutty Advance Technology Co., Ltd.             Inside the company (72) Inventor Susumu Takahashi             2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo             Nutty Advance Technology Co., Ltd.             Inside the company F-term (reference) 2H049 AA03 AA07 AA13 AA33 AA37                       AA43 AA48 AA51 AA55                 2H096 AA28 BA05 HA07 JA04                 4F204 AA44 AD04 AG05 AH73 EA03                       EA04 EB01 EB11 EK17 EK18

Claims (3)

[Claims] 1. A first step of forming a pattern of a photosensitive resin on a substrate, and an ultraviolet curable resin layer adhered on the pattern of the photosensitive resin to form the photosensitive resin on the ultraviolet curable resin layer. The second step of transferring the pattern, the third step of irradiating the pattern-transferred UV curable resin layer with ultraviolet rays to cure it, and the fourth step of peeling the cured UV curable resin layer from the substrate. A method for forming a pattern of an ultraviolet curable resin layer, which comprises at least a step. 2. An optical component comprising an ultraviolet curable resin layer formed in a pattern on an optical structure, wherein the ultraviolet curable resin layer is formed by the pattern forming method according to claim 1. An optical component characterized by being present. 3. A method of manufacturing an optical component comprising a pattern-formed UV-curable resin layer on an optical structure, the method comprising forming a pattern of a photosensitive resin on a substrate transparent or opaque to UV rays. Step and on the pattern of the photosensitive resin,
A second step of forming a UV-curable resin layer having an adhesive function in close contact and transferring the pattern of the photosensitive resin to the UV-curable resin layer, and an ultraviolet-transparent or opaque optical structure having the UV-curable resin layer. A third step of bonding on top,
At least a fourth step of irradiating the ultraviolet curable resin layer with ultraviolet rays to cure it and a fifth step of peeling the cured ultraviolet curable resin layer from the substrate, and at least the substrate and the optical structure. One is transparent to ultraviolet rays, and the ultraviolet irradiation in the fourth step is performed from either one or both sides of the substrate or the optical structure transparent to the ultraviolet rays.