KR20040017063A - Composition for making negative type liquid photoresist - Google Patents

Abstract

PURPOSE: Provided is a negative type liquid photoresist composition, which has excellent close contact force of fine lines and resolution and improved coating capability with no coating defects. CONSTITUTION: The negative type liquid photoresist composition comprises a binder polymer, a photopolymerization initiator, a photopolymerization monomer and an additive, wherein the bonder polymer is an acrylate polymer dissolved in the solvent of 1-methoxy-2-propanol. In particular, the acrylate polymer has a glass transition temperature of 100-150 deg.C, an acid value of 40-130 mgKOH/g and a weight average molecular weight of 20000-60000. Additionally, the additive is preferably triphenyl phosphate.

Description

Negative type liquid photoresist composition {Composition for making negative type liquid photoresist}

The present invention relates to a negative type liquid photoresist composition, and more particularly, using an acrylate polymer dissolved in a 1-methoxy-2-propanol solvent as a binder polymer and using triphenyl phosphate as an additive, fine wire adhesion and resolution The present invention relates to a negative liquid photoresist composition having excellent coating properties and no coating defects.

Negative liquid photoresist has higher fine wire adhesion and higher resolution than dry film. However, many conventional negative type liquid photoresists have not much fine line adhesion or resolution compared to dry films.

In addition, since the liquid photoresist uses a method of applying a liquid material on the substrate by a roll coating method or a dip coating method, the liquid should be uniformly coated and there should be no coating defects such as pinholes. However, conventional liquid photoresist products have a problem of not only poor coating property but also defects such as pinholes.

In the physical properties after exposure and development, thin wire adhesion and resolution are opposite to each other. Because the fine line adhesion is to be increased, the fine width line exposed while the unexposed part is completely washed out at the time of development should be attached without falling from the copper layer even with a small exposure amount. In order to increase the resolution, the unexposed portion adjacent to the exposed portion should be removed quickly under development conditions. If the viscosity of the resist is high or very high sensitivity, the resolution is degraded because the resist is not quickly removed from the boundary portion. That is, the resist between the exposed portion and the unexposed portion must have a large difference in developability under a certain development condition so that the fine wire adhesion and resolution can be made at the same time.

In order to satisfy these properties at the same time, a resist composition such as a binder polymer or monomer should have good adhesiveness to the copper plate and have appropriate developability when contacted with a developer.

Techniques for solving this technical problem and improving fine line adhesion and resolution have been disclosed. For example, US Pat. No. 6,037,100 attempts to improve adhesion by using a polyester film whose surface smoothness is controlled instead of polyethylene as a protective film of dry film, and copper (copper) in US Pat. No. 6,271,595. A method of enhancing adhesion by adding a germanium oxide layer was introduced.No. 6,103,449 was introduced through the introduction of a binder polymer that generates an acid by ultraviolet exposure, and in No. 5,935,761, a water-soluble monomer and fat-soluble. The method of optimizing the ratio of monomers and the content of the reactive group was used to improve fine wire adhesion and resolution. These techniques can be said to be the introduction of new ones in the component raw materials, the chemical structure change of existing raw materials, and the preparation of a crude liquid to optimize their component ratios.

However, the above-described conventional techniques have poor coating properties of the negative type liquid photoresist, so that the coating surface is uneven, and it is difficult to obtain a fine wire adhesion of 10 microns and a resolution of 20 microns.

Therefore, it is difficult to meet the demands of advanced information and communication device companies that demand continuous high resolution thin film PCB. Advanced chemical knowledge and compositional techniques for liquid photoresist are required to improve resolution to at least 20 microns and fine wire adhesion to 10 microns.

Therefore, the present invention provides a high resolution and high adhesion negative liquid photoresist required for making a circuit shape as the density of printed circuit boards and the density of circuit lines increase with the development of semiconductor packaging technology. The aim is to provide a good negative type liquid photoresist that is compatible with the purpose of having a coating defect.

The negative liquid photoresist composition of the present invention for achieving the above object contains a binder polymer, a photopolymerization initiator, a photopolymerization monomer and an additive, wherein the binder polymer is an acrylic dissolved in a 1-methoxy-2-propanol solvent. It is characterized by being a late polymer.

The present invention will be described in more detail as follows.

In general, the photoresist composition is composed of a binder polymer, a photopolymerization monomer, a photopolymerization initiator and additives. If you look specifically at this as follows.

(1) binder polymer

First, the binder polymers in the photoresist composition components and the monomers that can be used to synthesize them are discussed.

Examples of the binder polymer include acrylic polymers, polyesters, polyurethanes, and the like. Of these, methacryl-based copolymer (copolymer with ethylenically unsaturated carboxylic acid or other monomer, if necessary), which is a kind of acrylic polymer, is important. Methacrylic copolymers containing acetoacetyl group may also be used for the methacrylic copolymer.

Methacrylic monomers usable for synthesizing methacryl-based copolymers include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, Cyclohexyl methacrylate, benzyl methacrylate, dimethyl amino ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate and the like.

Among the ethylenically unsaturated carboxylic acid monomers, monoacrylic acids such as acrylic acid, methacrylic acid and crotonic acid are widely used. Dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid or anhydrides thereof, half esters and the like can also be used. Of these, acrylic acid and methacrylic acid are particularly used and exhibit excellent physical properties. In the case of the weak alkali developing photoresist resin, the amount of ethylenically unsaturated carboxylic acid is used in an amount of 15 to 30% by weight (acid value: 100 to 200 mgKOH / g).

Other copolymerizable monomers are acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, alkylvinyl ether and the like.

The negative liquid photoresist is generally dried at 110 ° C. for about 10 minutes after coating, and the resist should be very hard so that the resists do not stick together even when several substrates are stacked after storage. In general, the hardness of the liquid photoresist after drying should have a value of 2H or more. In order for the hardness of the resist to have a value of 2H or more after drying, the glass transition temperature of the binder polymer should be at least 110 ° C. This is because the entire photoresist composition contains not only a binder polymer but also a low molecular compound such as a single molecule and an oligomer, so that the glass transition temperature of the entire composition in which they are mixed is much lower than the glass transition temperature of the binder polymer alone.

In the present invention, the binder polymer having various glass transition temperatures was used to make the composition, and then the hardness was measured to select the optimum binder polymer.

If the glass transition temperature of the binder polymer is too high, the resist is too hard to break, peeling may occur during etching, and underplating defects may occur during plating. On the other hand, if the glass transition temperature of the binder polymer is too low, there is a problem that the hardness of the resist is lowered.

When selecting a binder polymer, the molecular weight and acid value as well as the glass transition temperature are very important. If the molecular weight is too small, fine wire adhesion and etching resistance may be weakened, while if the molecular weight is too large, the developing speed will be slow and the resolution will be poor. If the acid value is too small, there is a problem with the development. If the acid value is too high, the developing speed becomes too fast.

Therefore, it is necessary to design the binder polymer in accordance with the conditions such as molecular weight, glass transition temperature, acid value, etc. of the binder polymer in order to obtain a suitable development speed, resolution, hardness after drying.

In the present invention, the optimum binder polymer obtained through such a series of processes is an acrylate binder polymer dissolved in a 1-methoxy-2-propanol solvent, having a glass transition temperature of 100 to 150 ° C, and an acid value of 40 to 130 mgKOH / g. The weight average molecular weight is 20,000 to 60,000.

When acrylate binder polymer dissolved in 1-methoxy-2-propanol solvent is used, there is almost no smell and toxicity, so it has excellent workability and lowers the surface tension of crude liquid to improve leveling during coating. It is desirable to obtain the effect of increasing the adhesion to.

(2) photopolymerization monomer

As the photopolymerization monomer, an ethylenically unsaturated compound is included, and the ethylenically unsaturated compound includes a polyfunctional monomer and a monofunctional monomer.

As the polyfunctional monomer, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, propylene glycol dimethacrylate, polypropylene glycol dimethacrylate, butylene glycol dimethacrylate , 1,6-hexane glycol dimethacrylate, trimethylolpropane trimethacrylate, glycerin dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol penta Methacrylate, 2,2-bis (4-methacryloxydiethoxyphenyl) propane, ethylene glycol diglycidyl ether dimethacrylate, diethylene glycol diglycidyl ether dimethacrylate, phthalic acid diglyci Diester ester dimethacrylate, glycerin polyglycidyl ether polymethacrylate, etc. are mentioned.

An appropriate amount of the monofunctional monomer can be used together with the polyfunctional monomer. Examples of monofunctional monomers include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate, 2-methacryloyloxy-2hydroxypropyl phthalate, 3-chloro 2-hydroxypropyl methacrylate, glycerin monomethacrylate, 2-methacryloyl oxyethyl acid phosphate, methacrylate of a phthalic acid derivative, N-methylol methacrylamide, etc. are mentioned.

The amount of an ethylenically unsaturated compound is about 40-100 weight part with respect to 100 weight part of binder polymers by weight ratio. Use of less ethylenically unsaturated compounds results in less photocuring, lower resist flexibility and slower development. On the other hand, when a large amount of ethylenically unsaturated compound is used, the viscosity and low temperature flowability of the crude liquid are increased and the peeling rate is slowed.

(3) photopolymerization initiator

As photopolymerization initiator, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin phenyl ether, benzyl diphenyl disulfide, benzyl dimethyl ketal, anthraquinone, naphthoquinone, 3, 3-dimethyl-4-methoxybenzophenol, benzophenol, p, p'-bis (dimethylamino) benzophenone, p, p'-diethylaminobenzophenol, pivalon ethyl ether, 1,1-dichloroacetophenone , Dimer of hexaaryl-imidazole, 2,2'-diethoxyacetophenol, 2,2'-dichloro-4-phenoxyacetophenone, phenyl glyoxylate, α-hydroxy-isobutylphenone, dibenzospan , 1- (4-isopropylphenyl) -2-hydroxy-2-methyl-1-propanone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, tri -Bromo phenyl sulfone, tribromomethylphenyl sulfone, etc. are mentioned.

The amount of the photoinitiator added is preferably 1 to 20 parts by weight based on 100 parts by weight of the total amount of the binder polymer and the photopolymerizable monomer.

(4) additives

Volatile organics are compatible with the photoresist composition and should not interfere with film formability when coating the photoresist composition. Representative examples thereof include plasticizers used as softening agents such as vinyl chloride resin. Specific examples of the phthalic ester type include dimethyl phthalate, diheptyl phthalate, dioctyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, diisononyl phthalate, ethyl phthalethyl glycolate, dimethyl isophthalate, dichlorohexyl phthalate, and the like. Esters of fatty acids or aromatic acids, for example dioctyl adipate, diisobutyl adipate, dibutyl adipate, diisodecyl adipate, dibutyl diglycol adipate, dibutyl sebacate, dioctyl sebacate Etc.

Other softeners include glycerol triacetate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, tris-chloroethyl phosphate, tris-dichloropropyl phosphate, triphenyl phosphate, tricresyl phosphate, Tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, xylenyl diphenyl phosphate, trirylyl phosphate, tricetyl phosphate, tristearyl phosphate, trioleyl phosphite, dibutyl-butyl phosphonate, Di (2-ethylhexyl) phosphonate, 2-ethylhexyl-2-ethylhexyl phosphonate, isopropyl acid phosphate, butyric acid phosphate, dibutyl acid phosphate, monobutyl acid phosphate, octylic acid phosphate, dioctyl phosphate , Isodecyl phosphate, monoisode Seal phosphate, decanoic acid phosphate and the like.

As the softening agent, volatile organic compounds such as glycerin, trimethylolpropane, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and dipropylene glycol can be used, and lower alkyl ethers, lower fatty acid esters, higher fatty acids and these Esters, higher fatty alcohols or esters thereof may also be used.

As described above, depending on the form of the photoresist composition, the volatile organic material may be used within a range in which the coating property is not impaired. The weight ratio of the photoresist composition and the volatile organic material is usually 70:30 to 30:70.

On the other hand, when phenylacetic acid is added as an additive to improve fine wire adhesion, the resist becomes sticky after drying, but maleic anhydride becomes hard on the contrary. When additives are usually present alone or in the crude liquid, their properties change significantly. That is, the physical properties of the resist layer after drying vary greatly depending on whether the compatibility between the additive and other crude liquid constituent compounds (binder polymer, monomer, etc.) is good or bad. That is, if the additive has good compatibility with the binder polymer, the monomer, etc., the resist layer becomes sticky, and the poorer the compatibility, the greater the sole property of the additive.

However, when triphenyl phosphate is added, the fine wire adhesion force synergistic effect is very excellent without affecting the hardness or viscosity of the resist. In the case where 2.0% of triphenylphosphate was added to the total crude solid content, the break point was 20%.

Therefore, triphenyl phosphate is preferably added in an amount of 0.1 to 5.0%, preferably 0.1 to 2.0% as an additive.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

Example 1

In the present invention, after drying, a negative type liquid photoresist having a thickness of 10 microns and a composition of Table 1 was prepared, followed by roll coating, drying and exposing using a neomask-free Kolon artwork. The working conditions at this time are as follows.

Workshop temperature: 23 ± 2 ℃

PCB base size: 600mm × 400mm

Roll Coating: Line Speed 6m / min

Drying: 110 ℃, dried for 10 minutes

Parallel light exposure machine: Perkin-Elmer TM OB7120 (5kW)

Exposure dose: Exposure dose under artwork and exposure machine Myler film

Sensitivity: 21 steps

Artwork: High resolution artwork without protective neomask

Developer: 1.0 wt% sodium carbonate

Temperature: 30 ± 1 ℃

Break point: 50%

Developer spray pressure: 1.0kgf / ㎠

In the case of a dry film (Comparative Example 1: U.S. Patent No. 6,037,100), general lamination conditions were used, and the drying, exposure, and developing conditions were the same as the above operating conditions.

Furtherance Content (% by weight) Binder polymer Acrylate polymer dissolved in 1-methoxy-2-propanol solvent 24 Photopolymerization initiator Benzophenone 4,4-bisdiethylamino benzophenonetoluene sulfonic acid monohydrate diamond green GH 2.01.03.00.50.5 Photopolymerization monomer APG-400BPE-500 5.51.6 additive Triphenylphosphate 1.9 solvent 1-methoxy-2-propanol 60.0

Comparative Example 1: U.S. Patent No. 6,037,100

A product using a polyester film that satisfies the following conditions as a protective film for dry film.

3.0 nm ≤ SRa ≤ 50 nm

50 nm ≤Spv ≤500 nm

Where SRa is the average surface roughness of the film and Spv is the height difference between the peak and the valley

Comparative Example 2: U.S. Patent No. 6,271,595

A layer of copper germanide, germanium oxide, germanium nitride, and the like is coated on the copper layer, followed by silicon oxide or silicon nitride. (The above patent is not a case of negative photoresist coating but a silicon coating. Although related to, it can be referred to negative photoresist coating)

Comparative Example 3: US Patent No. 6,103,449

A composition using an alkali soluble binder polymer with a triazine additive for generating photo acid by ultraviolet exposure and a curing agent for reducing solubility in the presence of acid.

Comparative Example 4: U.S. Patent 5,935,761

The ratio of 2,2-bis [4- (acryloxy polyethoxy) phenyl] propane, a water-soluble monomer, is 3-15% (weight ratio to solids). Composition used as.

In the case of the present invention using the negative type liquid photoresist of the composition of Table 1 and the conventional liquid photoresist of Comparative Examples 1 to 4 were developed, the resist properties were compared, and the results are shown in Table 2 below.

Coating defect Hardness after drying 1/1 resolution when thin line is 10 micron 1/1 resolution at 12 micron Example 1 None 3H 10 micron 12 micron Comparative Example 1 - - 13 micron 15 micron Comparative Example 2 Poor leveling 2H 15 micron 18 micron Comparative Example 3 None 2H 18 micron 20 micron Comparative Example 4 Pinhole generation 1H 19 micron 22 micron

From the results in Table 2, when developed using the negative liquid photoresist according to the present invention, the fine wire adhesion and resolution is excellent. According to the prior art it can be seen that there is a problem that the thin line adhesion and the resolution is relatively low.

Examples 2 to 6 and Comparative Example 5

A negative type liquid photoresist was prepared in the same manner as in Example 1, but developed while changing the content ratio of triphenyl phosphate as an additive, as shown in Table 3 below, and then comparing the resist properties to the results in Table 3 below. Indicated.

Triphenyl phosphate content (weight ratio to solids) Coating defect Hardness after drying 1/1 resolution with 10 microns 1/1 resolution at 12 micron Example 2 0.1% None 3H 12 micron 14 micron Example 3 0.5% None 3H 11 micron 13 micron Example 4 1.0% None 2H 10 micron 12 micron Example 5 2.0% None 2H 12 micron 14 micron Example 6 5.0% None 1H 15 micron 17 micron Comparative Example 5 7.0% None B 22 micron 25 micron

From the results of Table 3, it can be seen that there is a problem that the fine wire adhesion increases as triphenyl phosphate is added as an additive, but the resolution is sharply reduced when the amount is excessive.

As described in detail above, in the case of applying the acrylate polymer dissolved in the 1-methoxy-2-propanol solvent as the binder polymer according to the present invention, the fine wire adhesion and resolution is excellent, the coating property is improved, there is no coating defect, When triphenyl phosphate is added here as an additive, the fine wire adhesive force synergistic effect is very excellent.

Claims (4)

In a negative liquid photoresist composition containing a binder polymer, a photopolymerization initiator, a photopolymerization monomer and an additive, The binder polymer is a negative type liquid photoresist composition, characterized in that the acrylate polymer dissolved in 1-methoxy-2-propanol solvent. The negative type liquid photoresist composition of claim 1, wherein the acrylate polymer has a glass transition temperature of 100 to 150 ° C., an acid value of 40 to 130 mgKOH / g, and a weight average molecular weight of 20,000 to 60,000. The negative type liquid photoresist composition of claim 1, wherein the additive comprises triphenylphosphate. The negative type liquid photoresist composition according to claim 3, wherein the triphenylphosphate content is 0.1 to 5% by weight relative to the solid content.