JPS60166946A - Photosensitive resin composition and formation of pattern having refractive index difference by using it - Google Patents

Abstract

PURPOSE:To obtain a useful element changeable in solubility and optical properties by using a combination of a specified acrylate or methacrylate homopolymer or copolymer, and benzaldehyde or benzophenone. CONSTITUTION:A photosensitive rein compsn. contains a homopolymer of 3,3- dimethylallyl (meth)acrylate or a copolymer with other vinyl monomer contg. this monomer in an amt. of >=5wt%, contg. said dimethylallyl groups having residual double bonds, and one of optionally substd. benzaldehyde and benzophenone (BP) derivs. represented by formulae I -IV in which each of X1-X6 is H, 1-6C alkyl or alkoxy or haloalkyl, or aryloxy, or halogen; and in II, when X1 and X2 are not H, this X and the CHO group must not be adjacent to each other. Such a compsn. is dissolved in a solvent, applied, and dried to obtain a coat film. This film is imagewise exposed to X-rays, or the like, and heated in reduced pressure to remove BP or the like at the unexposed part out of the film, and to combine BP with the polymer at the exposed parts. As a result, since the difference of refrastive indices between the exposed parts and the unexposed parts, it can be used for light guides, etc., and a pattern having a distribution of refractive indices can be obtained by using a lens-shaped patterns at the time of irradiation, and dissolving off the unexposed parts.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photosensitive resin composition and a pattern creation method using the same.

Conventionally, various types of photosensitive resin compositions have been proposed, and have been applied to photolithography, integrated circuits, paints, etc.
It is used in various industrial fields.

Conventionally known photosensitive polymers can be classified according to their composition: (1) photosensitive compound + polymer type, (2) polymer type with a photosensitive group, (3) photopolymerizable composition type.

(As for those belonging to 11, for example, dichromate +
There are polymer compounds, diazo or azide compounds, ten polymer compounds, etc., and the photosensitive compound is activated by light and reacts with the polymer compound, making use of the fact that it becomes a composition with different properties than before irradiation with light. It is something.

Items belonging to (2) include, for example, polyvinyl cinnamate or similar compounds, or polymers having a diazo group or a 7:) do group, which utilize crosslinking between polymers and collapse of polymers by light.

(3) Many systems of mixtures of photopolymerization initiators and polymerizable monomers are known as Vci. However, many of the photosensitive resins mentioned above change properties such as solubility by exposure to light. The main aim is to change
Taking advantage of the fact that the photosensitive area becomes less soluble or more soluble due to exposure to light, a pattern of protrusions and recesses is often formed by removing the unexposed or exposed areas using a solvent.

We, the inventors, have completed the present invention as a result of our search for a photosensitive resin composition that brings about a change in K, optical properties, especially a change in refractive index, in addition to a change in solubility, which was mainly used in the prior art. It is something.

That is, one object of the present invention is to provide a novel photosensitive resin composition, and another object is to provide a pattern forming method using the above-mentioned photosensitive resin composition.

According to the present invention, these objects are: (a) a homopolymer of 3,3-dimethylallyl ester of (meth)acrylic acid or a 3,3-dimethylallyl ester of (meth)acrylic acid;
- A copolymer with another vinyl monomer containing 5% by weight or more of dimethyl 7lyl ester, substantially [
The double bond of the 3,3-dimethylallyl group remains (
Co)polymer.

and (b) a photosensitive resin composition containing one or more types of unsubstituted or substituted benzaldehyde or pensyfunone.

and (a) 3,3-dimethyl of (meth)acrylic acid 7
A homopolymer of lyle ester or a copolymer with another vinyl monomer containing 5% by weight or more of 3,3-dimethylallyl ester of (meth)acrylic acid, which contains 1c3,3-dimethyl7 in the substantially trapped polymer. A film consisting of a photosensitive resin composition containing a (co)polymer in which a double bond of a lyl group remains, and (b) one or more of unsubstituted or substituted benzaldehyde or habe/siphenon, or A transparent material whose surface is a film of the photosensitive resin is selectively irradiated with active ultraviolet rays at specific positions, and then heated under normal pressure or reduced pressure to remove the compound (b) from the unexposed areas. This is achieved by a pattern creation method characterized by removal.

The (co)polymer of (a) of the composition of the present invention contains 5% by weight or more of dimethyl 7lyl ester of acrylic acid or methacrylic acid (hereinafter abbreviated as bunyl ester) in the monomer, and contains prenyl ester in the polymer. It is a homopolymer or a copolymer in which the groups do not substantially participate in polymerization and virtually all the double bonds of the prenyl groups remain. The seven monomers used as comonomers include methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 7 mil methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxybuvir methacrylate. , 2-methoxyethyl methacrylate, benzyl tutaacrylate dilylate, methacrylic acid 2
-dimethyl 7minoethyl, 2-diethyl methacrylate 7
Methacrylic esters such as minoethyl, acrylic acid, methyl acrylate, ethyl 7-acrylate, propyl acrylate, methyl acrylate, 2-ethylhexyl 7-acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, phenyl acrylate Examples include acrylic acid esters such as methacrylic acid 7mide, acrylic acid amide, diacetone acrylic 7mide, stinine, α-methylstyrene, vinyltoluene, 7crypnitrile, methacrylateril, and the like.

When selecting a comonomer, any comonomer may be used as long as it can be radically copolymerized with prenyl methacrylate, and a desired one can be used in consideration of the physical properties of the copolymer and the copolymer reactant after exposure ◇ Prenyl (meth) 7 If the acrylate is contained in the hexamer in an amount of 5% by weight or less, the object of the present invention cannot be achieved because the physical properties change during the reaction with the photosensitive compound as described above is not noticeable. A copolymer in which the double bond of the prenyl group remains can be easily synthesized by conventional radical polymerization. This is due to the extremely low radical polymerizability of the prenyl group. However, since the hydrogen on the methyl group or methylene group adjacent to the double bond of the prenyl group is easily abstracted by radicals, a chain transfer reaction may occur to these positions, resulting in a change in the structure of the original prenyl group. However, the loss of prenyl groups resulting from such reactions is acceptable. In the present invention, the meaning that the double bond of the 3,3-dimethylallyl group substantially remains means that the double bond remains, and an unsaturated bond becomes a saturated bond due to a polymerization reaction or a crosslinking reaction. This means that it has not changed,
Furthermore, even if a small portion is lost due to polymerization or crosslinking, it is acceptable as long as most of it remains and there is no major difference in physical properties.

The photosensitive compound used as component (b) of the photosensitive resin composition of the present invention is substituted or unsubstituted benzaldehyde or benzophenone.

For example benzo7-one, 2>-1 or 4-coolbenzophenone, 2-, a- or 4-bromobenzophenone, 4,4'-dichlorobenzophenone, 2,4- or 3,4-dichlorobenzophenone, 4 -Methylbenzophenone, 4-ethylbenzophenone, 4-propylbenzophenone, 4-t7'thylbenzophenone,
4-Schiff μhexylbenzophenone, 4-trifluorop
Methylbenzo7&non, 4,4'-dimethylbenzophenone, 4-nodoxybenzophenone, 3,4-dimethoxybenzophenone, 3,4,5-trimethoxybenzophenone, 3,4,5-)dimethoxy3'-chlor Benzophenones such as benzophenone, benzaldehyde.

2-13- or 4-chlorobenzaldehyde.

2.4->3.4- or 3.5-dichlorobenzaldehyde, 2-cy3- or 4-boombenzaldehyde, 4-methylbenzaldehyde, 4-t-butylbenzaldehyde, 4-cyclohexylbenzaldehyde, 2
-73-Matabanma 4-methoxybenzaldehyde, 3,
4-dimethoxybenzfuldehyde+, 3,4.5-
) Benzaldehydes such as rimethoxybenzaldehyde, 4-trifluoromethylbenzaldehyde, 3-phenoxybenzaldehyde, 3-hydroxybenzaldehyde, 4-cyanobenzaldehyde, phthalaldehyde, isophthalaldehyde, terephthalaldehyde, 4.
7-thalaldehydes such as 5-dimethylphthalaldehyde and 4,5-dichlorophthalaldehyde, 3-benzoylbenzophenone, 4-benzoylbenzophenone, 4-
Benzoylbenzophenones such as chlor-4'-benzoylbenzophenone can be used.

Among these benzaldehydes or benzyfunones, the following general formulas (I) to (■) (II) CN) (However, in formulas (1) to (IV) K, X1 to X6 are hydrogen and carbon atoms 1 to 6 represents an alkyl group, an alkoxy group having 1 to 6 carbon atoms, an allyloxy group, a haloalkyl group having 1 to 6 carbon atoms, or a halogen element, and when Xl or X2 in (I) is a group other than hydrogen, CHO
Compounds having no groups other than H, aldehyde or ketone groups at positions adjacent to aldehyde or ketone groups, such as those represented by (assuming the groups are located at non-adjacent positions), are advantageous because they have relatively high photosensitivity. Among these compounds, benzaldehyde and benzophene, which are the simplest chemical compounds, are preferred compounds from various viewpoints such as ease of availability, ease of purification, and photosensitivity.

The composition of the present invention is a photosensitive resin composition consisting of a combination of the above-mentioned component (a) and component (b), and by irradiating this composition with ultraviolet rays, the polymer compound and the photosensitive compound are combined. It is presumed that the properties change from before exposure due to bonding through reaction.

The photochemical reaction pressure between the photosensitive compound and the polymer compound in the present invention is not clear, but to explain it using pensifunone as an example, as shown in 7. It is estimated that the main reaction is a 1:1 cyclization reaction caused by light. The ratio of the aromatic ketone or aldehyde to the double bond derived from the prenyl group is approximately 1:1, with an appropriate range of 1:3 to 3:1.0 It is illegal to use too much of the photosensitive compound. Also, if it is too small, the effect will be small.

The composition can be obtained, for example, by dissolving a photosensitive compound and a polymer compound in a solvent and removing the solvent. For example, if the solution is applied and dried, a coating film of the composition of the present invention can be obtained. can get.

Exposure of the compositions of the invention can be carried out using ultraviolet radiation, especially at wavelengths of 300.
Ultraviolet rays of nm to 400 nm are effective, and high-pressure mercury lamps, ultra-high-pressure mercury lamps, N2 gas lasers, etc. are used as appropriate.

The present invention further provides methods of manufacturing devices useful for optical applications. Various photosensitive resins have been developed in the past, but as mentioned above, the main aim of most of them is to change properties such as solubility by exposure to light. Although the present invention has such characteristics, its major feature is its optical properties, and in particular, the ability to easily create a pattern having a difference in refractive index. As a method for aiming at such a refractive index change, for example, a low (or high) refractive index monomer is mixed with a photosensitizer in a high (or low) refractive index polymer, and the low (or high) refractive index is changed. There is a method of photosensitizing polymerization and then removing unreacted polymers, but this method generally has poor compatibility between polymers and tends to cause phase separation, whitening, etc., so it is not suitable for optical applications. There are problems with using it. The method of the present invention has few problems such as compatibility and is a method that can easily produce transparent films.

In the present invention, a film of the photosensitive resin composition or an object whose surface is a film of the photosensitive resin composition is irradiated with ultraviolet rays in a desired shape, and then the film or object is heated to irradiate the ultraviolet rays. This is a method of creating a pattern with a different refractive index in a desired shape by removing unreacted photosensitive compounds present in areas that were not irradiated.

The photosensitive resin composition of the present invention changes its solubility in various solvents or its color when irradiated with ultraviolet rays, so it is possible to use these changes, but it is particularly useful to utilize changes in the refractive index. It is an application. However, it is not possible to achieve a very large change in refractive index by simply irradiating ultraviolet rays. The present inventors have investigated various methods for removing unreacted photosensitive compounds from films, and have found that by heating under normal pressure or reduced pressure, unreacted photosensitive compounds can be removed without impairing the transparency of the film. It has been found that compounds can be removed and properties such as solvent resistance of the film are improved. The heat treatment conditions are determined taking into account the physical properties of the photosensitive compound to be removed, the concentration of the photosensitive compound, the thickness of the film, the heat resistance of the film, etc., and it is difficult to express it in general terms, but for example, when benzophenone is heated to 40 PI (R
To process a film with a thickness of 100 μm containing
The unreacted photosensitive compound was sufficiently removed by reducing the pressure to 3rrLmHg with C and leaving it for 4 hours. Ultraviolet rays can be irradiated using a high-pressure mercury lamp, ultra-high-pressure mercury lamp, or N2-
This can be done by using an ultraviolet laser such as a laser. At this time, if a mask having a lens-shaped, prism-shaped, or circuit-shaped pattern is used, a pattern having a refractive index difference of each shape can be created. Among them, by using a mask having a desired linear pattern, it becomes a useful material for producing various elements for optical communication, which has shown remarkable progress in recent years. By using the method of the present invention, phase separation and the like that are harmful to light propagation are less likely to occur, resulting in less light transmission loss. In this case, if a copolymer with a relatively low refractive index, such as a copolymer of prenyl methacrylate and MMA, is used, and a compound with a relatively high refractive index, such as benzophenone, is used as the photosensitive compound, the photosensitive area will remain unexposed. A pattern with a higher refractive index than the other parts can be obtained, and a material with a relatively high refractive index, such as a copolymer of prenyl methacrylate and styrene, is used as the reverse pressure copolymer, and 4-trifluoromethylbenzaldehyde is used as the photosensitive compound. When a compound with a relatively low refractive index is used, a pattern can be obtained in which the exposed areas have a lower refractive index than the unexposed areas.

Synthesis Example 1゜In a test tube, 5 g of methyl methacrylate, 10 g of prenyl methacrylate, 1511 g of 7zobisisobutyronitrile
After adding 45 g of dioxane and purging the inside of the test tube with N2, the tube was sealed and heated in an oil bath at 58° C. for 23 hours. When the residual rate of 7mer after the reaction was measured with Gask P and the change rate of each monomer was calculated, the change rate of MMA was 47.
The rate of change of 1% prenyl methacrylate was 53.5 inches, indicating almost the same degree of polymerization reactivity. The state after the completion of the polymerization reaction was uniform, and no precipitation of insoluble matter was observed. 77 tons of 120+/m were added to this polymer solution, and the 77 tons of added solution was gradually dropped into 250 m/m of methanol with stirring to precipitate the polymer. After drying, a solid polymer of 8.0 mOF was obtained. The infrared spectrum of this polymer shows an absorption at 16807 m-' that is presumed to be based on the C=c stretching vibration of the prenyl group, and together with the fact that this polymer is solvent soluble, the prenyl group is substantially consumed in the crosslinking reaction. It is presumed that it remains in the polymer without any oxidation. This polymer was dissolved in chloroform and the intrinsic viscosity was measured [
η) = 0.5835.

Synthesis Example 2゜5g of prenyl methacrylate in a test tube, 2.2.3゜3
- 5 g of tetrafluopopyl methacrylate, azobisin butyronitrile LO1n9 and dioxane 24
．． Prepare li+, replace with N2, seal the tube, and boil at 70'C for 2 hours.
Polymerization was carried out for 2 hours. The conversion ratio of each monomer to polymer was 90.3% of prenyl methacrylate, 96.4% of 2.2.3.3-tetrafluoroprupyl methacrylate (v-).

Examples of blended compositions are given below, along with data showing the photosensitivity of the compositions.

Example 1 Polymer 51!9 of Synthesis Example 1 was dissolved in 15.9 dioxane to obtain a homogeneous solution. 0.216 g of benzophenone was dissolved in 2 g of this solution to obtain a solution of the photosensitive resin composition. This solution was applied onto a flat piece of glass held horizontally and dried at room temperature. - After drying overnight, a coating film with a thickness of about 100 μm was formed on the glass plate. A part of this coating film is covered with a film that does not transmit ultraviolet rays, and
Ultraviolet rays were irradiated at a distance of 4 hours from 0W high-pressure water #ff1 (emission length 5 degrees). After 6 hours of irradiation, the cap was removed, placed in a vacuum dryer purged with N2, and heated at 100°C for 1 hour.
The temperature was maintained for an additional 4 hours at 100° C. and 3 fflmHg. After leaving it to cool, I took it out, peeled the film off the glass plate, and measured the refractive index using a 7-piece refractometer.
The refractive index of the part covered with a film that does not transmit ultraviolet rays is 1.
．． 5062, whereas the refractive index of the portion irradiated with ultraviolet rays was 1.5344. This is because in areas that are not irradiated with ultraviolet rays, benzophenone is expelled from the film by sublimation during heating under reduced pressure;
This is thought to be because benzophenone was bonded to the polymer compound through a photoreaction in the areas irradiated with ultraviolet rays, and was therefore left behind in the film. Therefore, by comparing the refractive index of the irradiated portion and the unirradiated portion, a standard for comparison of photosensitivity can be obtained.

Example 2-18 A test similar to that of Example was conducted using various photosensitive compounds instead of benzophenone in Example 1. Table 1 shows the refractive index of the exposed area and the area to be exposed after heating.
c Show.

Example 30 After exposure in Example 1, the film was immersed in a mixed solution of 77 tons and ethanol, and the unexposed parts of the film were dissolved, but the exposed parts were not.

Example 31 A film having a width of 100 μm as shown in FIG.
It has a pattern consisting of a straight part with a radius of μm and a curved part with a radius of curvature of 1 cIn.
Ultraviolet light was irradiated with a high-pressure mercury lamp.

After irradiation, place the glass and film (while still touching) in a vacuum dryer and dry at 100°C for 1 hour at normal pressure.
rLm) Ig for 4 hours. When the dried film was peeled off from the glass and the edges of the pattern were irradiated with light from a helium-neon laser squeezed through a lens, it was observed that the light bent along the shape of the pattern. In addition, the light introduced from one end of the pattern (the end face (al) in Figure 1) is detected at the other end of the straight part (B) and the end faces (b'), (b') obtained by cutting the straight part. When the attenuation of light inside the waveguide was measured by this method, it was found to be 0 at a wavelength of 800 nm.
．． It was 2dB/crIL.

Example 32 When a branch circuit pattern as shown in Fig. 2 was created by the same operation as in Example 31, it was found that the light incident from (cl)
, (observed to come out from el.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a pattern mask, and FIG. 2 is an explanatory diagram of a pattern of a branch circuit according to an embodiment of the present invention. Patent applicant: Kyowa Gas Chemical Industry Co., Ltd. Figure 1 Figure 2

Claims (1)

[Scope of Claims] (1) (a) Homopolymer of 3,3-dimethyl 7#lyl ester of (meth)acrylic acid or 5-fold 41% 3,3-dimethyl 7#lyl ester of (meth)acrylic acid A (co)polymer with other vinyl monomers containing the above, in which a double bond of 3,3-dimethyl7lyl group substantially remains in the polymer, and (b) a non-vinyl monomer. A photosensitive resin composition containing one or more substituted or substituted benzaldehydes or benzophenones. +21 The compound of +01 has the following general formula (I) or I
The photosensitive resin composition according to claim 1, which is at least one type of compound represented by I/). (However, in formulas (I) to (ff), X1 to X6 are hydrogen,
represents a furkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a 7lyloxy group, a herofurkyl group having 1 to 6 carbon atoms, or a halogen element, and in (1), X or X2 is other than hydrogen; In the case of a group, the X and the CHO group are not adjacent to each other. ) The photosensitive resin composition according to claim 1 or 2, wherein the compound (3) (1) is benzaldehyde or benzophenone. (4) The photosensitive resin composition according to claims 1 to 3, wherein the (co)polymer in (a) is a (co)polymer of 3,3-dimethyl 7lyl methacrylate and methyl methacrylate. thing. (5) (a) A homopolymer of 3,3-dimethylallyl ester of (meth)acrylic acid or (meth)acrylic acid f) Other vinyl monomers containing swt% or more of 3,3-dimethyl 7lyl ester A (co)polymer in which a double bond of a 3,3-dimethylallyl group substantially remains in the polymer, and (b) a benzaldehyde which is unsubstituted or has a substituent or Ultraviolet rays are selectively irradiated to specific positions of a film made of a photosensitive resin composition containing one or more benzophenones or a transparent material whose surface is a film of the photosensitive resin, and then under normal pressure or reduced pressure. A pattern creation method characterized by removing the compound (b) from the unexposed portions by heat treatment. (6) The method according to claim 5, wherein the pattern is a film-like optical waveguide.