JP2008122897A - Photomask for negative exposure and photocuring type pattern produced using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photomask for negative exposure which permits production of a photocuring type pattern without peeling the pattern, and a photocuring type pattern produced using the same. <P>SOLUTION: The photomask 21 for negative exposure includes an objective pattern 24 and a dummy pattern 25, wherein the objective pattern 24 comprises openings 22 and light shielding portions 23, and the dummy pattern 25 is disposed in such a way that it comes in contact with at least one side of the objective pattern 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a negative exposure photomask, a pattern forming method using the photomask, and a photocurable pattern produced using the method.

  In high-speed and high-density signal transmission between electronic devices and between wiring boards, signal transmission interference and attenuation become barriers in conventional transmission using electric wiring, and the limits of high-speed and high-density are beginning to appear. In order to overcome this, a technology for connecting electronic elements and wiring boards with light, so-called optical interconnection, has been proposed, and development of polymer optical waveguide materials used therefor has been actively conducted.

Among the polymer optical waveguide materials, those having a dry film shape are excellent in terms of handleability and increase in area. For example, Patent Document 1 and Patent Document 2 disclose photosensitive dry film polymer optical waveguide materials. Has been proposed.
A general configuration of the dry film-like polymer optical waveguide material is shown in FIG. A dry film-like polymer optical waveguide material 1 has a photosensitive layer 2 that is generally a core layer or a clad layer obtained by coating and drying a resin varnish on a base film 3 to form a film. It has a protective film (separator) 4 on it, and is wound up into a roll shape and manufactured. The optical waveguide fabrication process using this dry film polymer optical waveguide material is as follows:
(1) Affixing a resin film for forming a lower clad layer on a substrate and curing the lower clad layer (FIG. 2 (a)),
(2) Peeling of the base film in the resin film for forming the lower clad layer (FIG. 2 (b)),
(3) Affixing a resin film for forming a core layer on the lower cladding layer (FIG. 2 (c)),
(4) Core pattern exposure (FIG. 2 (d)),
(5) Peeling of the base film in the core layer forming resin film (FIG. 2 (e)),
(6) Development (FIG. 2 (f)),
(7) Affixing and curing an upper clad layer forming resin film for covering the core pattern (FIG. 2 (g)),
(8) Peeling of the base film in the resin film for forming the upper clad layer (FIG. 2 (h)),
In the study by the inventors, in the base film peeling step of the core layer forming resin film of (5), the core pattern is peeled together when the base film is peeled off. There was a problem of ending up.

This is because the photomask as shown in FIG. 3, that is, the photomask 21 consisting only of the target pattern opening 22 and the light-shielding portion 23 is used, so that the pattern formed by exposure is isolated in an island shape. In particular, in the case of a thin line pattern having a width of several tens of μm such as an optical waveguide, there may be a case where the lower surface of the pattern, that is, the lower clad, cannot be sufficiently adhered. In such a case, a necessary pattern may be peeled off as the base film is peeled off.
In addition to the dry film optical waveguide material described above, a liquid optical waveguide material may be used as the photosensitive optical waveguide material. In this case, however, the photomask is prevented from being contaminated, or an acrylic material is oxygen-free. In order to prevent curing from being hindered, it is necessary to provide a cover film for blocking oxygen on the photosensitive optical waveguide material. In this case, since the cover film needs to be peeled off after exposure and curing as in the case of the above-described base film, a necessary pattern may be peeled off as the cover film is peeled off.

JP-A-6-258537 JP 2006-22317 A

  In view of the above-mentioned problems, the present invention is manufactured using a negative exposure photomask capable of producing a photocurable pattern without peeling of a target pattern, a pattern forming method using the photomask, and the method. An object is to provide a photocurable pattern.

As a result of intensive studies, the present inventors have found that the above problem can be solved by providing a dummy pattern so as to be in contact with a part of the target pattern.
That is, the present invention
[1] A negative exposure photomask including a target pattern and a dummy pattern, wherein the target pattern includes an opening portion and a light shielding portion, and a dummy is formed so as to be in contact with at least one side of the target pattern. Photomask for negative exposure with a pattern,
[2] The negative exposure photomask according to [1], wherein the width of the dummy pattern is twice or more the width of the opening of the target pattern,
[3] Using the photomask for negative exposure described in [1] or [2] above, a desired pattern is formed on the photosensitive resin composition with a base film or a cover film via the base film or the cover film. A method for forming a photocurable pattern comprising a step of exposing the substrate film and a step of peeling the substrate film or the cover film after the exposure,
[4] The photocurable pattern obtained by the method according to [3] above, and [5] The photocurable pattern according to [4] above, wherein the photocurable pattern is an optical waveguide,
Is to provide.

  According to the present invention, it is possible to produce a photocurable pattern that does not peel off the target pattern.

  The photomask of the present invention is a negative exposure photomask including a target pattern and a dummy pattern, and is characterized in that the dummy pattern is disposed so as to be in contact with at least one side of the target pattern. Hereinafter, it demonstrates in detail using FIG. Here, the case where the photocurable pattern is an optical waveguide core pattern will be described as an example, but it can be applied as long as it can be cured by a method of forming a pattern by being cured by irradiation with actinic rays. Therefore, the photocuring pattern of the present invention is not limited to the optical waveguide, and can be applied to various resist patterns such as an etching resist, an electrical insulating resist, a solder resist, and a liquid crystal member.

FIG. 4A shows a photomask of the present invention. The photomask 21 of the present invention includes a target pattern (in a dotted line region, a pattern region 24) and a dummy pattern 25, and the target pattern (pattern region 24) is formed by an opening 22 and a light shielding portion 23. . The target pattern (pattern region 24) and the dummy pattern 25 are arranged so that the dummy pattern 25 is in contact with at least one side of the target pattern (pattern region 24).
By using such a mask pattern, as shown in FIGS. 4B and 4C, the core pattern 32 is held by the peripheral pattern fixing edge 37, so that the optical waveguide core layer is formed. The problem that a pattern will peel at the time of peeling of the base film of a resin film can be solved.
That is, the AA ′ cross section of FIG. 4 (b) is shown in FIG. 4 (d). When the base film 36 is peeled off, the core pattern 32 is held by the peripheral pattern fixing edge 37, and the core pattern 32 does not peel off together with the base film 36. Therefore, as shown in the sectional view after development in FIG. 4E, the core pattern 32 can be reliably disposed on the lower clad layer 34.

  The width d of the pattern fixing edge 37 is not particularly limited as long as it is within a range in which a necessary pattern exposure region 24 can be secured in a predetermined mask dimension. However, the width d of the pattern fixing edge 37 should be at least twice the width of the core pattern 32 to be formed. For example, a large contact area with the lower cladding layer 34 can be ensured, so that a sufficient effect can be obtained. From this viewpoint, the edge width d is more preferably 5 times or more the width of the core pattern 32, and more preferably 10 times or more. That is, in the photomask, the width d of the dummy pattern is preferably at least twice the width of the opening 22 constituting the target pattern, more preferably at least five times, particularly at least ten times. preferable.

4 shows an example in which the dummy pattern 25 is provided on the four sides of the pattern area 24. However, the dummy pattern 25 has at least one side of the pattern area 24, for example, FIG. 5 (the dummy pattern is arranged on three sides). As shown in FIG. 6 (arranged on the same side) and FIG. 7 (arranged on the same side). In this case, peeling of the base film after exposure is preferable because peeling of the target pattern is less likely to occur from either side of the provided dummy pattern.
Further, in the example shown in FIG. 4A, the dummy pattern is provided up to the outer periphery of the photomask. However, as long as the dummy pattern has a desired width, the dummy pattern does not cover the outer periphery of the photomask as shown in FIG. May be provided.

  Furthermore, the dummy pattern may be provided inside the pattern region 24 as shown in FIG. 9, and in this case, the target pattern can be fixed more firmly. Furthermore, the dummy pattern may have an independent shape as long as it is in contact with the target pattern as shown in FIG. In the production of the optical waveguide, an upper clad layer is provided after the core pattern is formed, but an island-shaped core pattern can be formed by making the dummy pattern independent as shown in FIG. 10, thereby ensuring an air escape path. Therefore, there is an effect that air bubbles are eliminated when the upper clad layer is formed, and the occurrence of defects can be reduced.

Next, the manufacturing method of the optical waveguide using the photomask of this invention is demonstrated using FIG.
First, when a protective film is present on the substrate 11 composed of FR-4 substrate, polyimide, silicon, aluminum, copper, etc., the protective film is peeled off, and then the base film surface of the resin film for forming the lower cladding layer The resin film for lower clad layer formation is laminated | stacked by carrying out thermocompression-bonding on this board | substrate on this board | substrate. Here, it is preferable to laminate | stack under reduced pressure from the viewpoint of adhesiveness and followable | trackability. The heating temperature of the film is preferably 50 to 130 ° C., and the pressure bonding pressure is preferably about 0.1 to 1.0 MPa (1 to 10 kgf / cm ² ). There is no particular limitation. Next, the lower clad layer forming resin film is cured by light or heating to obtain the lower clad layer 12 (see FIG. 2A).

  Next, after peeling the base film 16 of the lower clad layer forming resin film (see FIG. 2B), the core layer forming resin film having a high refractive index is the same as the above lower clad layer forming resin film. (Refer FIG.2 (c)). Next, using the photomask of the present invention, that is, the photomask 21 in which the dummy pattern is arranged so as to contact at least one side of the peripheral portion of the target pattern, the base film 17 of the resin film for forming the core layer is interposed. Then, actinic rays are irradiated and exposed in the form of an image (see FIG. 2D). Examples of the active light source include known light sources that effectively emit ultraviolet rays, such as carbon arc lamps, mercury vapor arc lamps, ultrahigh pressure mercury lamps, high pressure mercury lamps, and xenon lamps.

Subsequently, if necessary, after the post-exposure heat treatment, the base film 17 of the resin film for forming the core layer is peeled off (see FIG. 2E). When the photomask of the present invention is used, the target core pattern 14 is not peeled off along with the base film 17 at the stage of peeling the base film 17.
In addition, when peeling this base film 17, you may peel this base film 17 on heating conditions as needed.

Next, the unexposed portion is removed and developed by wet development or the like (see FIG. 2F), and the core pattern 14 is formed. In the case of wet development, development is performed by a known method such as spraying, rocking immersion, brushing, and scraping using a developer suitable for the composition of the film, but the spray method is suitable for improving the resolution. .
Moreover, as a process after image development, the core pattern 14 may be further cured and used by performing heating at about 60 to 250 ° C. or exposure at about 0.1 to 1000 mJ / cm ² as necessary.

Thereafter, an upper clad forming resin film having a refractive index lower than that of the core film is laminated and cured in the same manner as the above lower clad forming resin film (see FIG. 2G), and the upper clad layer forming resin film The base film is peeled off (see FIG. 2 (h)). Thereafter, the upper cladding layer may be further cured by heating at about 60 to 250 ° C. or exposure at about 0.1 to 1000 mJ / cm ² as necessary.

  By using the photomask of the present invention to produce an optical waveguide by the process as described above, the core pattern is not peeled off when the base film in the resin film for forming the core layer is peeled off. A waveguide can be easily produced.

The photomask of the present invention can also be suitably used when a liquid optical waveguide material is used as the photosensitive optical waveguide material. In this case, a liquid optical waveguide material is used in place of the above-described clad layer forming resin film and core layer forming resin film. In this embodiment, after a liquid optical waveguide material is applied and dried, a cover film is provided for preventing contamination and preventing inhibition of curing by oxygen. The cover film is peeled off after exposure and curing. Therefore, in the step of forming the core layer, specifically, the following mode is adopted.
That is, after forming the lower cladding layer, a core layer forming resin solution having a high refractive index is applied and dried, and a cover film is provided thereon. The photomask of the present invention is laminated on the cover film, and actinic rays are irradiated and exposed in an image form through the cover film. Then, after performing heat processing as needed, this cover film is peeled. When the photomask of the present invention is used, the target core pattern is not peeled along with the cover film at the stage of peeling the cover film.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
(Varnish formulation)
A resin composition for the core layer and the clad layer was prepared with the formulation shown in Table 1, and 40 parts by mass of ethyl cellosolve as a solvent was added to the total amount to prepare a resin varnish for the core layer and the clad layer. .

* 1 Phenototoy YP-70; manufactured by Tohto Kasei Co., Ltd., bisphenol A / bisphenol F copolymer phenoxy resin * 2 A-BPEF; manufactured by Shin-Nakamura Kogyo Co., Ltd., 9,9-bis [4- (2- Acryloyloxyethoxy) phenyl] fluorene * 3 EA-1020; manufactured by Shin-Nakamura Kogyo Co., Ltd., bisphenol A type epoxy acrylate * 4 KRM-2110; manufactured by Shin-Nakamura Kogyo Co., Ltd., alicyclic diepoxycarboxylate * 5 Irgacure 819; manufactured by Ciba Specialty Chemicals Co., Ltd., bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide * 6 Irgacure 2959; manufactured by Ciba Specialty Chemicals Co., Ltd., 1- [4- (2- Hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-pro Down-1-one * 7 SP-170; Asahi Denka Co., triphenylsulfonium hexafluoroantimonate salt

(Preparation of a fatty film for forming an optical waveguide)
A polyethylene terephthalate film (trade name: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd., thickness: 50 μm) was used as a base film, and a coating machine (Multicoater M-200, Co., Ltd.) was formed on the non-treated surface. The resin varnish for clad was applied using Hirano Tech Seed) and dried at 80 ° C. for 10 minutes and then at 100 ° C. for 10 minutes to prepare a resin film for forming a clad layer.
Similarly, a core resin varnish was produced on a non-treated surface of a polyethylene terephthalate film (trade name: Cosmo Shine A1517, manufactured by Toyobo Co., Ltd., thickness: 16 μm) to obtain a core layer forming resin film. . At this time, the thickness of the resin layer can be arbitrarily adjusted by adjusting the gap of the coating machine. In this embodiment, the thickness after curing is 20 μm for the lower cladding layer, 70 μm for the upper cladding layer, and the core layer. It adjusted so that it might be set to 50 micrometers.

(Production of optical waveguide)
On a FR-4 substrate (trade name: MCL-E-679F, manufactured by Hitachi Chemical Co., Ltd.), a vacuum pressurizing laminator (manufactured by Meiki Seisakusho Co., Ltd., MVLP-500) was used, and the pressure was 0.4 MPa. A resin film for forming a lower clad layer is laminated so that the base film is on the upper surface under the conditions of a temperature of 50 ° C. and a pressurization time of 30 seconds, and an ultraviolet exposure machine (EXM-1172, manufactured by Oak Seisakusho). Ultraviolet rays (wavelength 365 nm) were irradiated at 300 mJ / cm ² and further heated at 80 ° C. for 10 minutes to photocur the lower clad layer forming resin film (see FIG. 2A).

Next, after the base film of the resin film for forming the lower clad layer is peeled off (see FIG. 2B), the core is formed on the lower clad layer under the same conditions as those for laminating the resin film for forming the lower clad layer. A layer-forming resin film was laminated (see FIG. 2C). Subsequently, using a negative photomask having a mask opening (dummy pattern 25) in the periphery of the pattern exposure region (pattern region 24) as shown in FIG. The substrate was irradiated with 1000 mJ / cm ^{2 of} ultraviolet rays (wavelength 365 nm) with the above ultraviolet exposure machine (see FIG. 2D). Immediately after that, post-exposure heating (PEB) was performed at 80 ° C. for 5 minutes, and the base film of the core-forming resin film was peeled off (see FIG. 2E).
In the negative photomask used here, the width of the target pattern opening 22 is 50 μm, the width of the light-shielding portion 23 is 200 μm, the pattern region 24 is 125 mm long, 125 mm wide, and the dummy pattern (opening) 25 is wide. d is 1 mm.

Subsequently, the core pattern was developed with an 8 to 2 mass ratio mixed solvent of propylene glycol monomethyl ether acetate and N, N-dimethylacetamide (see FIG. 2 (f)). Isopropyl alcohol was used for washing the developer.
Next, the upper clad layer-forming resin film is laminated under the same laminating conditions as the lower clad layer-forming resin film (see FIG. 2G), and ultraviolet rays (wavelength 365 nm) are 1000 mJ / cm with the above-described ultraviolet exposure machine. ² irradiated. Thereafter, the base film of the resin film for forming the upper clad layer was peeled off (see FIG. 2H), and finally, heat treatment was performed at 160 ° C. for 1 hour to produce an optical waveguide.

  In addition, when the refractive index of the core layer and the clad layer was measured by a prism coupler (Model2010) manufactured by Metricon, the core layer was 1.584 and the clad layer was 1.550 at a wavelength of 830 nm.

  The optical waveguide produced in this way was not peeled out of 120 cores when the base film of the core layer forming resin film was peeled off. In addition, the propagation loss of the manufactured optical waveguide was determined by using a cut-back method using a surface-emitting laser of 850 nm ((EXFO, FLS-300-01-VCL) as a light source, and Advantest Co., Ltd., Q82214 as a light receiving sensor. (Measurement waveguide length 5, 3, 2 cm, incident fiber: GI-50 / 125 multimode fiber (NA = 0.20), output fiber: SI-114 / 125 (NA = 0.22)) 0.09 dB / cm.

Comparative Example 1
In Example 1, an optical waveguide was used in the same manner as in Example 1 except that a photomask without a mask opening provided at the periphery of the pattern region 24 as shown in FIG. 3 was used as the negative photomask. Produced. As a result, although the propagation loss was the same as 0.09 dB / cm, when the base film of the core layer forming resin film was peeled, 10 pieces of peeled out of the total 120 cores.

  According to the present invention, since a photocurable pattern can be produced without peeling of the pattern, it can be applied to various resist patterns such as optical waveguides, etching resists, electrical insulation resists, solder resists, and liquid crystal members. Especially in the case of a thin line pattern with a width of several tens of μm, such as an optical waveguide, the adhesion between the pattern and its lower surface tends to be insufficient, and the pattern required when peeling the base film easily peels off together with the base film. The invention is particularly effective.

It is a figure explaining a dry film-form optical waveguide material. It is a figure explaining the manufacturing method of the optical waveguide using a dry film-form optical waveguide material. It is a figure explaining the conventional photomask. It is a figure explaining the photomask of this invention and the core layer pattern formed using this. It is a figure explaining the photomask of this invention. It is a figure explaining the photomask of this invention. It is a figure explaining the photomask of this invention. It is a figure explaining the photomask of this invention. It is a figure explaining the photomask of this invention. It is a figure explaining the photomask of this invention.

Explanation of symbols

1; dry film-like optical waveguide material 2; photosensitive layer (core layer or clad layer)
3; base film 4; protective film (separator)
11; Substrate 12; Lower clad layer 13; Core layer 14; Core pattern 15; Upper clad layers 16, 17, 18; Substrate film 21; Photomask 22; Target pattern opening 23; 25; dummy pattern (opening)
31; Optical waveguide 32; Core layer exposure part (core pattern)
33; core layer unexposed portion 34; clad layer 35; substrate 36; base film 37; edge for fixing core pattern

Claims (5)

  A negative exposure photomask including a target pattern and a dummy pattern, wherein the target pattern includes an opening and a light shielding portion, and the dummy pattern is disposed so as to be in contact with at least one side of the target pattern Photomask for negative exposure.   2. The negative exposure photomask according to claim 1, wherein the width of the dummy pattern is at least twice the width of the opening of the target pattern.   The process of exposing a desired pattern to the photosensitive resin composition with a base film or a cover film using the negative exposure photomask of Claim 1 or Claim 2 via this base film or cover film. And the formation method of the photocurable pattern which has the process of peeling this base film or cover film after exposure.   A photocurable pattern obtained by the method according to claim 3.   The photocurable pattern according to claim 4, wherein the photocurable pattern is an optical waveguide.

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