JPS6295526A - Photosensitive resin composition and method for preparing pattern using the composition - Google Patents

Abstract

PURPOSE:To enable an exposed part to have a high refractive index by incorporating a polymer or copolymer having >=2mol% specified structural unit and at least one compd. selected from aromatic aldehydes and aromatic ketones having unsubstituted or substituted groups. CONSTITUTION:The compsn. contains (A) a polymer or copolymer contg. >=2mol% structural unit expressed by the formula I and (B) at least one compd. selected from aromatic aldehydes or aromatic ketones having unsubstituted or substituted groups. Representative compds. (B) are unsubstituted or substituted benzaldehyde, benzophenone, or their derivs. The proportion of the polymer (A) to the compd. (B) is not particularly restricted, but is generally 10:1 to 1:10 by weight, and the molar ratio of (B) to the alcohol residue having double bonds in the polymer (A) is regulated to be 10:1-1:20. By this constitution, than the refractive index of the unexposed part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photosensitive resin composition suitable for forming a pattern having both a refractive index difference and a relief structure, and a method for producing a pattern using the same.

[Conventional technology]

Many of the conventionally known photosensitive resins are composed of a compound with a photosensitive group and a polymer compound, or are a polymer compound with a photosensitive group, and many of them are subject to crosslinking reactions and polymer collapse reactions caused by light. Relief patterns have been created by taking advantage of the fact that exposed areas become less soluble or more soluble when exposed to light, and by removing non-exposed areas or exposed areas using a solvent. Also, as an example of special photosensitive resin,
A photolocking method using a conductor made of a copolymer of 2-naphthalenethiol-doped methyl methacrylate and methacrylic-dispersed glycidyl is known (W, J,
Toml 1son et al. applied-Physic
s Letters, Volume 26, No. 6, No. 303-306
Page, 1975). In this method, a coating film is formed from a resin doped with a relatively volatile substance with a higher refractive index, and then UV rays are irradiated to remove the doped material in the exposed areas. This method forms a pattern with a difference in refractive index between exposed and non-exposed areas by evaporating and removing the dope material at the base of the knee.According to this report, the film thickness in exposed areas is smaller than that in semi-exposed areas. is about 10%
reported to be increasing.

[Problems to be solved by the invention]

The former, ordinary photosensitive resin, is not intended to provide a difference in refractive index, so the difference in refractive index in the resulting relief pattern is almost non-existent, or even if there is, it is extremely small. ”
Furthermore, the photosensitive resin employed in the latter photolocking method does not have a sufficient refractive index of 2 between exposed and non-exposed areas and 1 degree change in thickness of uneven areas. In addition, when a photosensitive resin is used as a plastic optical element, transparency is required. Furthermore, the photosensitive resin composition is required to exhibit a quick response rate when exposed to original irradiation and to form a clear pattern.

The object of the present invention is to provide a novel photosensitive resin composition which produces a surface relief structure simultaneously with a change in refractive index, in particular when the refractive index of the exposed part is higher than the refractive index of the unexposed part. It is possible to provide a photosensitive resin composition that has a thicker layer than the unexposed portion, that is, has a convex structure, has a fast reaction rate, and can draw a clear pattern. Another object of the present invention is to provide a method for producing a pattern having both a refractive index difference and a relief structure using the photosensitive resin composition described above. Another object of the present invention is to provide a pattern with excellent optical transparency.

[Means for solving problems]

The inventors of the present invention conducted extensive studies in view of the above objectives, and found that
A photosensitive resin composition consisting of an acrylic acid or methacrylic acid ester polymer or copolymer having a specific photoreactive double bond in the alcohol residue of the ester and an aromatic ketone or aromatic aldehyde is photoreactive. I found out that it is expensive. Furthermore, after the photosensitive composition is selectively irradiated with ultraviolet rays, unreacted aromatic ketones or aromatic aldehydes are removed to obtain a large refractive index difference and unevenness difference between exposed and unexposed areas. I discovered that.

That is, the first aspect of the present invention relates to a photosensitive resin composition, and relates to a polymer or copolymer (hereinafter simply referred to as polymer A) containing 2 or more moles of structural units of general formula I, and (-CH2-C- ) 1
ooy CB) It is characterized by containing one or more compounds selected from aromatic aldehydes and aromatic ketones having non-slightly substituted or substituent groups (hereinafter simply referred to as compound ('B)).

In formula 7, R4, R5 and R6 are hydrogen atoms or al\
A second invention of the present invention is a method for producing a pattern using the photosensitive resin composition, including (a) forming a thin film of the photosensitive resin composition; The process of periodically irradiating ultraviolet rays →
It is characterized in that the steps of removing compound (B) are performed sequentially.

The polymer (A) in the composition of the present invention contains a structural unit having a double bond within the alcohol astringent group of the ester. The structural unit) is usually 2 moles or more, preferably 5 moles or more.

In the general formula (■) or (■) representing the substituent Y, R1-R6
When is an alkyl group, the alkyl group may have a branch and may have any substituent. The number of carbon atoms in the alkyl group is not particularly limited, but it is generally preferable to be a lower alkyl group having 8 or less carbon atoms. Further, Z represents a divalent group having two or more carbon atoms, and is preferably an optionally branched alkylene group having 2 to 8 carbon atoms.

Examples of preferred 1θ substituents Y include the following. Groups with three carbon atoms such as allyl groups; 2-butenyl groups,
Groups with 4 carbon atoms such as 3-butenyl group and 2-methyl-2-propenyl group; 2-hebutenyl & 3-hebutenyl group, 4-hebutenyl group, 2-methyl-2-butenyl group,
Groups having 5 carbon atoms such as 2-ethyl-2-propenyl group, 2-methyl-3-phthynyl group, 1゜2-dimethyl-2-propenyl group; 2-hexenyl group, 3-hexenyl group,
4-hexenyl group, 5-hexenyl group, 1.1-
Dimethyl-2-butenyl group, 1,2-dimethyl-2=butenyl group, 1.3-dimethyl-2-butenyl group, 2.3
-Dimethyl-2-butenyl group, 3-methyl-2-heptenyl group, 2-methyl-2-heptenyl group, etc. with 6 carbon atoms
or cycloalkenyl groups such as 2-methyl-2-cyclohexenyl group and 3) thyl-2-cyclohexenyl group.

The 1M method is not particularly limited as long as the above polymer (Al has the structure of general formula (1)).That is, a polymer containing acrylic acid or methacrylic acid is used, and an alcohol having a double bond in the molecule, for example, 2 - Can be obtained by reacting with an alcohol such as butynol (polymer esterification reaction).However, polymers obtained by homopolymerization of acrylic acid derivatives corresponding to general formula (1) or copolymerization with other comonomers is particularly preferably used. Examples of such acrylic acid derivatives include allyl methacrylate,
Allyl acrylate, 2-(t or 3)-butenyl 7-methacrylate, 2-(or 3)-butenyl acrylate, 2-methyl-2-propenyl methacrylate, 2-methyl-2-propenyl acrylate, 2-(or 3)-butenyl acrylate, 4)-pebutenyl methacrylate, 2 (or 3 or 4)-acrylate, 2-methyl-(2 or 3)
-butenyl methacrylate, 2-methyl-(2 or 3
)-butenyl acrylate, 2-ethyl-2-propenyl methacrylate, 2-ethyl-2-propenyl acrylate, 1,2-dimethyl-2-butenyl methacrylate), 1,2-dimethyl-2-7'ropenyl Acrylate, 2 (or 3 or 4 or 5)-hexenyl methacrylate, 2 (t or 3″! or 4 or 5)-hexenyl acrylate, 1,1 (or 1.2 or 1.
3 or 2.3)-dimethyl-2-butenyl methacrylate), 1.1-(t or 1.2 or 1,3 or 2,
3)-dimethyl-2-butenyl acrylate, 2(or 3)-methyl-2-hebutenyl methacrylate, 2(
Acrylic acid derivatives in which alcohol residues are chained, such as t or 3)-methyl-2-hebutenyl acrylate;
Examples include acrylic acid derivatives in which alcohol residues are cyclic, such as 2(41-13)-methyl-2-cyclohexenyl methacrylate and 2(or 3)-methyl-2-cyclohexenyl acrylate. Among these, allyl methacrylate, 2-methyl-2-propenyl methacrylate, 2-butenyl methacrylate, 2-hexenyl methacrylate, and 3-hexenyl methacrylate have alcohol residues that are easy to obtain, Preferred for ease of ester synthesis.

The comonomer to be subjected to copolymerization may be any monomer that copolymerizes with the above-mentioned acrylic ester derivatives, such as methacrylic acid; methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, Methacrylic acid alkyl esters such as cyclohexyl methacrylate; acrylic! ! Examples include acrylic acid alkyl esters such as methyl 2-niacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and cyclohexyl acrylate, methacrylic acid amide, acryl amide, and substituted styrenes such as styrene: α-methylstyrene. These comonomers may be substituted with fluorine.

Synthesis of a polymer in which carbon-carbon double bonds remain in the alcohol residues described above involves adding two or more carbon-carbon double bonds in cis or trans to the alcohol residues of the acrylic acid derivative monomer. If the alkyl group is substituted, it can generally be synthesized by radical C synthesis or anionic polymerization, and if the carbon-carbon double bond constitutes a vinyl group or vinylidene group, it can be easily synthesized by anionic polymerization. . During polymerization, the carbon-carbon double bonds may be slightly changed due to side reactions, but it is preferable that the double bonds in the polymer (A) do not substantially participate in the copolymerization. There are no particular restrictions on the molecular weight of the polymer (N), but it is generally in the range of 1,000 to 1,000,000 in terms of number average molecular weight. ) A remarkable change in properties is observed.

Examples of the compound (B) in the composition of the present invention include unsubstituted or substituted benzaldehyde, benzophenone, or good conductors thereof, and when expressed as a general formula, it is represented by the following formula (1) or (v).

(') (V) (However, in 2N or (V), X1 to X6 represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, an allyloxy group, or a nitrogen atom. , X7 to X10 represent a hydrogen atom or a hydrogen atom, and n represents 0 or an integer) In the above formula, preferred compounds are X1 to XIO hydrogen;
are 1 or 2 compounds.

A suitable example of compound CB+ is benzophenone:3
- Straight 4-methylbenzophenone, 3 or 4-methquine benzophenone, 3.3'-4 or 4°4'-dimethylbenzophenone, 3.3't or 4.4'-dimethoxybenzophenone, 2.3 -! or 4-chlorobenzophenone, 3.4. ．． 5-) IJ Methylbenzophenone, substituted benzophenones such as 3,4.5-trimethoxybenzophenone, 3-benzoylbenzophenone: 3-(34 or 4-methylbenzoyl)-3' or 4' methylbenzophenone , 3-(3 or 4-methoxybenzoyl)-3't or 4'methylbenzophenone, 3,3'-dibenzoylbenzophenone, etc. fkl!
3-benzoylbenzophenones, benzaldehyde,
Substituted benzaldehydes such as 3- or 4-methylbenzaldehyde, 3- or 4-methylbenzaldehyde, 3,4-dimethylbenzaldehyde, and 3,4-dimethoxybenzaldehyde are mentioned. These compounds (B)
Since it does not have a substituent such as a methyl group, ethyl group, or inopropyl group at the ortho position to the carbonyl group, it has the advantage that side reactions such as intramolecular hydrogen abstraction due to light irradiation are less likely to occur. In the present invention, benzaldehyde, benzophenone, 3
-Benzoylbenzophenone and 3,3'-dibenzoylbenzophenone are particularly preferred from the viewpoint of photosensitivity and ease of synthesis;
Dibenzoylbenzophenone is particularly preferred from the viewpoint of photosensitivity, refractive index difference, formation of relief structure, etc.
).

The composition of the present invention is a photosensitive resin composition comprising a combination of the above-mentioned polymer (N) and compound (B), and by irradiating this composition with light of, for example, 300 to 420 nm,
N and (B) react and the properties change. In the present invention, the photochemical reaction between (N and (B)) is expressed by the following formula:
The Paterno BLichi reaction is the main reaction.

(In the formula, ph is a phenyl group, R, R', R", ht"
and t' represents a hydrogen atom or a 1n substituent) Therefore, the triplet energy of compound CB) is
It is necessary that the triplet energy is lower than the triplet energy of A).

Further, the excited triplet state of the compound (B) is generally required to have strong nff* properties, and compounds with strong ππ properties are not preferred. However, since the polymer G used in the present invention contains a reactive double bond in the alcohol residue, it has high reactivity, and has the advantage that it can achieve a large refractive index change and a large relief structure even in the early stage of the reaction. has.

Next, the details of the pattern forming method using the composition of the present invention will be described.

The polymer (A) and the compound (B) are completely dissolved in a solvent, and a coating film is formed by a general method such as the Caste-Fugu method, the bar code method, or the spin code method. If necessary, the bath agent is removed from the nuclear membrane under reduced pressure or by applying pressure to form a membrane of the composition of the present invention.

The loading/unloading may be a film or a thin film formed on a substrate. Various methods for forming the film can be selected depending on the desired thickness or form of the film.

- If the material is relatively thick, the casting method is selected, and if the material is thin, the bar code method or spin code method is selected, or other methods may be used. Polymer (A) and compound (
The ratio of B) is not particularly limited, but is generally 1 in terms of weight ratio.
The concave circle is arbitrarily selected from 0:1 to l゛10. The molar ratio of the compound (B) to the alcohol residue having a double bond in the polymer (AJ) is arbitrarily selected within the range of 10:1 to 1:20, preferably 5:1 to 1. It is within the range of 10.

For exposure, an element of 300 to 420 nm is used. For example, a cylindrical mercury lamp (Mi day pressure mercury lamp), an N2 gas laser, a He-Cd gas laser, etc. are used as appropriate. The proposed exposure method is a method using a photomask, and a two-beam interference exposure method.
There are methods such as direct irradiation with a laser beam, which can be used as appropriate.

The present invention can be obtained by removing the compound (B) by any method after exposing the above-mentioned odor. For example, by treating the compound (B) in the non-exposed area and the unreacted compound (B) at 0°C to 120°C under reduced pressure or under normal temperature, the refractive index difference in the desired shape can be obtained. A complete collection of optically transparent clear patterns with relief structures! iru.

According to the pattern creation method of the present invention, the refractive index of the exposed area is larger than that of the unexposed area, and furthermore, the perforated part is thicker than the unexposed area and has a convex shape. ? ! It has the characteristic of being made of For example, optical waveguides with low propagation loss, diffraction gratings, and the like can be manufactured in arbitrary shapes. The present inventors studied methods for controlling the refractive index difference and the relief structure, and found that the composition of the present invention has the following characteristics: (1) the group F of the present invention;
Jy, the proportion of the polymer (integrated) in the product, the proportion of the @formation position represented by the general formula (1) and the proportion of the compound (B) in the body), (2) exposure time (3), or It was found that 0TfIl: can be arbitrarily controlled by a combination of the following.

Generally, when a compound with a large number of phenyl rings is used as the compound ('B) in the composition, or when a polymer (A) with a large number of non-conjugated double bonds is used, the difference in refractive index becomes large. Become. Further, the depth of the relief structure increases as the ratio of compound (B) to polymer (A) increases. Furthermore, the longer the reaction time, the more reaction occurs, and therefore both the refractive index difference and the depth of the relief structure become larger. However, it goes without saying that these conditions must be appropriately selected from the composition of the polymer (A) and compound (B) in the composition, the film thickness of the composition, and the like.

Since the composition of the present invention has extremely good optical transparency after exposure, it can be used as a material for manufacturing optical elements. Since Honkamei's compositions can have a large refractive wheel and relief structure at the same time, they can be used for optical waveguides, diffraction gratings, grating lenses, Fresnel lenses, hologram lenses, optical branch circuits, geodesic lenses, Lunepul lenses, etc. Available for

〔Example〕

Synthesis Example 1 A test tube was charged with 3 2-butenyl methacrylate, 52 methyl methacrylate, 8 η of azobisisobutyronitrile, and 232 dioxane after Nzfil conversion, and the tube was sealed and incubated in a water path at 55 to 60°C for 24 hours. heated for an hour. Then, pour the reaction solution into 5 od of acetone and incubate for 200 d.
The resulting polymer was precipitated with methanol. When the resulting polymer was dried, 502 was obtained. When the composition of this polymer was observed by NMR, it was found that the hydrogen at the carbon-carbon bond in the alcohol residue of 2-butenyl methacrylate was 5.5
~5.9 ppm, and it was confirmed that it was a copolymer of 2-butenyl methacrylate:methyl methacrylate=1F3.3 (molar ratio). The molecular weight of this polymer was determined to be 210,000 in number average molecular weight when measured by gel permeation chromatography.

Example 1 A composition consisting of 1 part of the polymer of Synthesis Example 1 and 1 part of 3-pair'/ilhensiphenone was dissolved in benzene and spin-coated onto a substrate to form a thin film of about 1.1 μm. This thin film was baked at 70° C. for 1 hour and exposed to a 250 W ultra-high pressure mercury lamp for 3 minutes through a chrome photomask. After exposure, remove the photomask and dry with a vacuum dryer at 95%.
After baking was performed at 0.2 wAHf for 3 hours to form a pattern.

After cooling, the adhesion between this No. 1 film and the substrate was good, and the He-
The refractive index was measured using a prism coupling method using a Ne laser, and the layer thickness and relief depth were measured using a dual beam interference microscope. The exposed area and the unexposed area were drawn as a clear pattern with a difference in unevenness and a difference in refractive index.

Patterns were formed in the same manner as described above except that the exposure time was varied between 0 and 30 minutes.

Measure the refractive index and relief depth in the same manner as described above,
The results are also shown in FIGS. 1 and 2.

Examples 2 to 6 0.7 to 2.0 μm consisting of a composition of the polymer (5) of Synthesis Row 1 and each compound (H) having one carbonyl group at a M ratio of 1:0.8 A thin film was prepared on a substrate and exposed for 18 minutes using an ultra-high pressure mercury lamp (250 W).

After exposure, (B) in the unexposed and unreacted areas was removed, and the refractive index and relief structure were measured in the same manner as in Example 1. These results are shown in Table 1.

The following margin Example 7 Polymers of various compositions (A
) was synthesized, and operations such as exposure were performed in the same manner as in Examples 2 to 6 using 3-benzoylbenzophenone as compound (B), and the refractive index and relief structure were measured. These results are shown in Table 2.

Table 2 Example 15 A composition consisting of 1 part of the polymer of Synthesis Example 1 and 1 part of 3-benzoylbenzophenone was formed on a substrate to a thickness of about 1.0 μm and exposed through a 10 μIn line-and-space photomask for a period of time. The same operation as in Example 1 was carried out except that the time period was changed to 18 minutes, and a transmission type phase Yukokin plot was made. This phase grating is a bimodulated refractive index phase grating consisting of a convex part with a film thickness of 1.20 μm and a refractive index of 1.548, and a four part film with a refractive index of 1.510 and a film thickness of 40.87 μm. When the diffraction efficiency was measured at 6328 μm), the 0th order light intensity was 0.295 and the ±1st order light intensity was 0.295. This result was in good agreement with the theoretical value of the form refractive index dual modulation type phase grating, and it was confirmed that a clear pattern was drawn. This phase grating can be used as a three-element splitter.

Example 16 A composition consisting of 1 part of the polymer of Synthesis Example 1 and 0.5 parts of benzophenone was formed on a glass substrate to a thickness of about 1 μm.
．． The same operation as in Example 1 was performed through a photomask having a linear pattern of = SO μm to produce a thin film optical waveguide. This thin film optical waveguide is a He-Ne laser T
It is a single mode in E mode, and the propagation loss is Q, 4d.
B/m was good.

〔Effect of the invention〕

According to the present invention, a photosensitive resin composition is provided that allows a pattern having a desired refractive index difference and relief structure to be produced in a short period of time. In addition, the photosensitive resin composition of the present invention has high sensitivity, and by removing unreacted portions after irradiation with light, the refractive index of the exposed portion is significantly higher than that of the unexposed portion, and the thickness of the exposed portion may be reduced. It has the effect of being able to draw a clear pattern that is significantly thicker than the non-g original portion.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the effects of the photosensitive resin of the present invention. Figure 1 shows the exposure time and the refractive index difference between exposed and non-exposed areas, and Figure 2 shows the exposure time and the difference in refractive index between exposed and non-exposed areas. This shows the difference in thickness between the exposed area and the unexposed area (difference in relief depth). Patented wheat flour Kuraray Co., Ltd.

Claims (1)

[Claims] 1) (A) A polymer or copolymer containing 2 mol% or more of the structural unit of the general formula I, and ▲ mathematical formulas, chemical formulas, tables, etc. ▼ I (wherein, X is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y is a substituent having a double bond or a cycloalkenyl group represented by the following general formula II or III.) (B) Unsubstituted or aromatic having a substituent A photosensitive resin composition containing one or more compounds selected from aldehydes and aromatic ketones. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ II (In the formula, R_1, R_2 and R_3 are each the same or different hydrogen atom or alkyl group, and Z is a divalent substituent having 2 or more carbon atoms.)▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ III (In the formula, R_4, R_5 and R_6 are hydrogen atoms or alkyl groups, and if R_6 is a hydrogen atom, R_
4 and R_5 are never methyl groups at the same time. 2) The composition according to claim 1, wherein the copolymer (A) is a copolymer with a saturated alkyl ester of acrylic acid or methacrylic acid. 3) The photosensitive resin composition according to claim 1, wherein the copolymer (A) is a copolymer of one or more methacrylates and methyl methacrylate. 4) The compound (B) is benzaldehyde, benzophenone, 3-benzoylbenzophenone or 3,3'-
Claim 1 which is dibenzoylbenzophenone
The composition according to item 1, 2 or 3. 5) (A) (A) Polymers or copolymers containing 2 mol% or more of the structural unit of the general formula I, and ▲ mathematical formulas, chemical formulas, tables, etc. ▼ I (where X is a hydrogen atom or the number of carbon atoms) 1 to 4 alkyl groups, and Y is a substituent having a double bond or a cycloalkenyl group represented by the following general formula II or III.) (B) Aromatic aldehyde and aromatic which are unsubstituted or have a substituent. a step of forming a thin film from a photosensitive resin composition containing one or more types of compounds selected from group ketones, (b) a step of selectively irradiating the thin film with ultraviolet rays, (c) a step of (B). A method for producing a pattern, characterized by sequentially performing steps for removing a compound. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ II (In the formula, R_1, R_2 and R_3 are each the same or different hydrogen atom or alkyl group, and Z is a divalent substituent having 2 or more carbon atoms.)▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ III (In the formula, R_4, R_5 and R_6 are hydrogen atoms or alkyl groups, and if R_6 is a hydrogen atom, R_
4 and R_5 are never methyl groups at the same time. ) 6) Claim 5 in which the compound of (B) is removed by evaporation.
Method for producing the pattern described in Section 2. 7) The method for producing a pattern according to claim 6, wherein the removing means is performed under reduced pressure and/or heating.