KR100316971B1 - Resin for chemically amplified resist - Google Patents

Abstract

The present invention relates to a resin for chemically amplified resist and a resist composition using the same.

The present invention provides a polymer resin represented by Formula 1 and a short wavelength sensitive photosensitive chemically amplified resist composition comprising the polymer resin.

[Formula 1]

The chemically amplified resist composition including the polymer resin represented by Chemical Formula 1 of the present invention may form a fine pattern of excellent resolution on a wafer in response to a short wavelength in a photolithography process.

Description

Chemical Amplified Resist Resin {RESIN FOR CHEMICALLY AMPLIFIED RESIST}

[Industrial use]

The present invention relates to a resin for chemically amplified resist and a resist composition comprising the same. In particular, the present invention relates to a novel polymer resin applicable to a chemically amplified resist composition capable of forming a fine pattern on a wafer in a photolithography process in response to a short wavelength and a resist composition using the same.

[Prior art]

In the manufacturing process of semiconductor devices, the photolithography process consists of applying a photoresist film to a substrate, transferring a pattern as previously designed, and composing an electronic circuit through an etching process that appropriately scrapes according to the transferred pattern. It is a process.

This photolithography process

a) the application | coating process of apply | coating uniformly the photosensitive resin composition to the surface of a board | substrate;

b) The solvent is evaporated from the applied photoresist film so that the photoresist film

Soft baking process;

c) repeatedly drawing circuit patterns on the mask using a light source such as ultraviolet light.

The substrate is exposed to the substrate while being shrunk and sequentially

An exposure step of transferring to an image;

d) physical properties, such as differences in solubility, depending on exposure to light from exposure.

A developing step of selectively removing the grown portions using a developing solution;

e) to more closely adhere the photoresist film remaining on the substrate after development

Hard baking process;

f) predetermined areas to impart electrical characteristics in accordance with the pattern of the developed substrate;

Etching the etching process; And

g) a stripping process for removing the unnecessary photoresist film after the etching operation

It includes.

Higher integration of semiconductor integrated circuits generally proceeds at four times the speed over three years, with dynamic random access memory (hereinafter referred to as DRAM) now producing 64 megabits of storage capacity, and development of gigabit DRAM also started. .

In the conventional 16 mega DRAM, a circuit line width technology of 0.5 μm was used, but in 64 mega DRAM, a circuit line width technology of 0.3 μm or less is used. It is becoming.

This requirement cannot be met by conventional photosensitive resin compositions consisting of quinonediazide-based photoactive materials and phenolic novolac resins, because the system has a large absorption at 300 nm or less and short wavelength exposure of 300 nm or less. This is because the pattern profile deteriorates significantly. Therefore, research is required for the implementation of steep patterns without the phenomenon of flow of pattern profiles.

In forming such a pattern profile, a step-and-feed aligner commonly called a stepper is widely used as an exposure apparatus. This exposure apparatus uses G line (436 nm) and I line (365 nm) of mercury light depending on the light source and excimer laser of short wavelengths KrF (248 nm) and ArF (193 nm). It is divided into dragons. In order to implement a fine pattern on the wafer, the resolution value R should be small. Basically, it is advantageous to use a short wavelength according to Equation 1 below.

[Equation 1]

R = κλ / NA

Where

κ is a constant, λ is the wavelength of light used (nm), and NA is the lens aberration.

In order to achieve high resolution below the quarter micron, resolution of photolithography should be improved. For this purpose, it is effective to use a short wavelength light source with a short wavelength and to increase the N.A of the optical lens of the exposure apparatus.

Therefore, a photosensitive resin composition using an excimer laser light source has been commercialized to cope with high resolution, and a chemically amplified resist is mainly used as a photosensitive resin for KrF and ArF excimer lasers.

The chemically amplified resist generates an acid in response to deep UV, and the generated acid decomposes a partially protected protecting group by heat assist and then generates an acid again. Due to this continuous reaction of acid, the concept of chemical amplification was introduced.

These chemically amplified resists are classified into negative and positive types.

Negative forms are known in the literature (Jour. Vacuum Science Technology., Vol. B6, 1988) to include alkali soluble binder resins, crosslinkers, acid generators and solvents as main components. In this kind of resist material, a spin film is usually used to form a resist film, and the resist film is soft baked, and then the pattern is exposed through a reticle so that acid is generated only in the irradiated portion. The acid is generated from the acid generator by post exposure baking, and since the acid activates the crosslinking agent, the binder resin becomes insoluble. Development is then carried out to form negative patterns.

Since the acid generated from the acid generator in the chemically amplified resist acts as a catalyst for activating a large amount of the crosslinking agent, high sensitivity is realized, and the absorption by the photosensitive agent is lower than that of the conventional photosensitive resin, thereby achieving high resolution. Furthermore, since it is possible to use a phenol resin as a binder resin similarly to the conventional photosensitive resin, there is also an advantage that the resistance is maintained in the dry etching step later. Such a negative chemically amplified resist is a three-component resist composed of a noblock resin, a melamine crosslinked resin, and an acid generator.

On the other hand, in the pattern formation method using the chemically amplified resist using the noblock phenol resin, the absorption effect by the binder resin and the crosslinked resin when the exposure light source is converted from the conventional G-ray and I-ray light sources to the excimer laser light source. The problem that this occurs and the formed pattern becomes a reverse taper is known from J. Vacuum Science Technology, Vol. B7, 1989.

As an alternative, a positive chemically amplified resist has been proposed (Proc. Spie., Vol 1262, p32, 1990). This chemically amplified resist is a high molecular compound comprising an acid generator which generates an acid when irradiated with a compound that reacts with the acid. This compound is a compound that easily decomposes with an acid, and has a high molecular compound having a low light absorption in a short wavelength region, such as a polyvinylphenol derivative, and thus the chemically amplified resist has more transparency, and Since the reaction of the resist proceeds by a chain reaction, it has high sensitivity and excellent resolution.

Such positive chemically amplified resists are chemically amplified resists composed of poly (hydroxystyrene) and onium salts blocked by t-BOC (tertiary-butoxy carbonyl) groups by Ito et al. (American Chemical society, 'polymers in electronics', ACS Sym. Series, No. 242.) and also by Ueno et al., Poly para-styreneoxytetrahydropyranyl (poly (p-styreneoxytetrahydropyranyl) and Chemically amplified resists composed of acid generators are known in the literature (Preparation of the 36th Japanese Society for Applied Physics, 1p-k-7, 1989), and are bisphenols substituted with noble resins and t-BOC groups by Schlegel et al. A three-component resist consisting of -A, pyrogallol methanesulfonic ester is known from the 37th Japanese Society of Applied Physics, 28p-ZE-4, 1990. Ryeonhan techniques is disclosed in Japan Patent Publication No. Hei 2-27660 call, Japanese Laid-Open Patent Publication No. Hei 5-232706, Japanese Unexamined Patent Publication No. Hei 5-249683, U.S. Patent No. 4,491,628 and U.S. Patent No. 5,310,619 or the like arc.

However, such chemically amplified resists have excellent resolution, but if the pattern of the micro pattern is post-exposure-bake to post-exposure-bake post-exposure, then the exposure to the substrate may occur. The problem that footing occurs due to the reaction may also appear.

Therefore, in the case of the resist composition to which the compound is applied, supplementation is necessary in terms of PED safety, and a resist composition to which a high molecular compound that exhibits higher sensitivity and resolution at wavelengths of 300 nm or less is required.

Accordingly, an object of the present invention is to form a fine pattern on the wafer in the photolithography process in response to deep UV in consideration of the above problems, and can be applied to a positive chemically amplified resist composition with enhanced PED safety It is to provide a novel polymer resin and a resist composition to which the same is applied.

[Means for solving the problem]

The present invention provides an alkali developable copolymer polymer resin represented by the following formula (1) to achieve the above object.

[Formula 1]

Where

R ₁ is chlorine, bromo, hydroxy, cyano, t-butoxy, CH ₂ NH ₂ , CONH ₂ ,

CH = NH, CH (OH) NH ₂ or C (OH) = NH,

R ₂ is hydrogen or methyl,

x is 0.1-0.9.

The copolymer has a weight average molecular weight (Mw) of 3,000 to 30,000, the dispersion can be synthesized by adjusting to 1.01 to 3.00 according to the synthesis method.

The substituted monomer used in the present invention exhibits sufficient development inhibitory ability in the non-exposed part, and exhibits the property that the substituent decomposes and dissolves in the developer by the action of an acid in the exposed part.

When the resin of the present invention is applied to the photosensitive composition, the composition

a) copolymer polymer resin represented by Formula 1

b) acid generators generating acid

c) organic solvents

It includes.

When the polymer resin of the present invention is applied to the photosensitive composition, it is preferable that 1 to 50% by weight is included in the resist composition.

The acid generators of b) include onium salts such as sulfonium salts and iodonium, N-iminosulfonates, disulfones, bisarylsulfonyldiazomethanes and arylcarbonylarylsulfonyl Diazomethanes and the like may be used, and the resist composition preferably contains 0.1 to 50% by weight of at least one selected from the photoacid generators.

Examples of the sulfonium salts are as follows.

, , ,

, , , , , ,

, ,

, ,

,

Examples of the iodonium salt are as follows.

, ,

, ,

Examples of the N-iminosulfonates are as follows.

, ,

,

Examples of the disulfones are as follows.

Wherein R is H, -CH ₃ or -C (CH ₃ ) ₃

Examples of the bisarylsulfonyl diazomethanes are as follows.

Wherein R is H, -CH ₃ or -C (CH ₃ ) ₃

Examples of the arylcarbonylarylsulfonyldiazomethanes are as follows.

Wherein R is H, -CH ₃ or -C (CH ₃ ) ₃

The organic solvent of c) is ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, ethyl ether acetate, n-butyl acetate, methyl isobutyl ketone, ethyl lactate, 3-ethoxy-ethylpropionate, 3 -Methoxy-methylpropionate, diglycol monoethyl ether, 2-heptanone, diacetone alcohol, β-methoxyisobutyric acid methyl ester, propylene glycol monomethyl ether, propylene glycol monomethyl propionate, methyl It may be selected from the group consisting of lactate, butyl lactate, ethyl pyruvate, γ-butyrolactone, 0.1 to 99% by weight in the composition.

In the photosensitive composition to which the polymer resin of the present invention is applied, a dissolution inhibitor may be added to improve dissolution inhibition of a non-exposed part. The use of a dissolution inhibitor contributes to the improvement of contrast by making the difference in solubility between the non-exposed part and the exposed part large. Such dissolution inhibiting additives may be added in an amount of 0.1 to 50% by weight based on the weight of the polymer resin of the present invention.

The action in the process for obtaining the fine pattern of the photosensitive composition to which the polymer resin of the present invention is applied is as follows.

When the photosensitive composition to which the polymer resin of the present invention is applied is formed with a thin thin film on a substrate such as a silicon wafer, and then treated with a basic aqueous solution, the solubility of the copolymer is low so that dissolution does not occur. However, when irradiated with a short wavelength beam, the acid generator in the photosensitive combination generates an acid, and the development-inhibiting substituent of the copolymer structure in the exposure region causes the decomposition by the addition of heat, causing the generation of acid again. As a result, one generated acid exhibits chemical amplification which causes several acid active degradation activities. As a result, the solubility of the copolymer is greatly increased in the exposed portion, and the difference in solubility of the non-exposed portion and the exposed portion occurs when developing with a basic aqueous solution. This action is advantageous in that resolution can be obtained that is superior to a composition using a conventional positive chemically amplified resist resin that is sensitive to the resolution and short wavelength obtained by conventional G-rays and I-rays.

The present invention will be described in detail with reference to the following Examples and Comparative Examples. However, these Examples are only for illustrating the present invention and the present invention is not limited thereto.

EXAMPLE

Example 1

Synthesis of 4-Cyanomethylstyrene (CyMS)

In a 500 ml four-necked flask equipped with a stirring rod, 49.01 g of sodium cyanide was mixed with 70.07 g of water and 50.96 g of ethanol, and the flask temperature was raised to 60 ° C. to completely dissolve sodium cyanide.

87.50 g of 4-chloromethyl styrene was slowly added to the solution, followed by reaction with stirring for 3 hours while maintaining the reaction temperature at 60 to 70 ° C.

After the reaction was completed, the reaction mixture was cooled to 40 ° C, and 100 g of diethyl ether was added to separate the diethyl ether layer.

The separated organic layer was extracted three times with 300 g of water, and the water layer was extracted with 50 g of diethyl ether and mixed with the organic layer.

The separated organic layer was dried with magnesium sulfate for 1 day, and then the organic solvent was removed using an evaporator to obtain 4-cyanomethylstyrene.

Yield was 80% yield, dark purple.

The synthesis is according to Scheme 1 below.

Scheme 1

Synthesis of 4- (1-cyanoethyl) styrene (CyES)

Potassium hydride (35% mineral oil) 9.75 was dissolved in 180 ml THF 500 ml four-necked flask equipped with a stirring rod, and 12.17 g of 4-cyanomethylstyrene was prepared in 50 ml THF for 1 hour. After slowly injecting and stirring for 1 hour, 5.3 ml of iodomethane was slowly added to the reaction solution, followed by stirring at room temperature for 24 hours.

After the reaction, 100 g of diethyl ether was added to separate the diethyl ether layer. The separated organic layer was extracted three times with 300 g of water, and the water layer was extracted with 50 g of diethyl ether and mixed with the organic layer.

Separation The obtained organic layer was dried with magnesium sulfate for 1 day and then the organic solvent was removed using an evaporator to obtain CyES at a yield of 80%.

The synthesis is according to Scheme 2 below.

Scheme 2

4- (2- (2-Cyano-4-t-butoxycarbonyl) butyl) styrene (CBCBS) Synthesis

After dissolving 62.89 g of CyES and 1.4 g of Triton nasal solution in 40 g of dioxane in a 500 ml four-necked flask equipped with a stirring rod, the reactor was kept at 60 ° C. and 102.54 g of t-butylacrylate was stirred for 30 minutes. Was added slowly, and stirred for 24 hours.

After the reaction, the solution was neutralized with a hydrochloric acid solution, the neutralized reaction solution was extracted three times with 100 g of diethyl ether and 300 g of water, and the water layer was extracted with 50 g of diethyl ether, and mixed with the organic layer.

The separated organic layer was dried with magnesium sulfate for 1 day, the organic solvent was removed by an evaporator, and the resultant was distilled under reduced pressure to remove unreacted material. It was.

The synthesis is according to Scheme 3 below.

Scheme 3

Synthesis of poly (HS-co-CBCBS) polymer resin

A temperature controller and a nitrogen injector were attached to a 500 ml four-necked flask equipped with a reflux condenser, 300 ml of THF was added thereto, and nitrogen was added thereto, followed by stirring for 30 minutes.

48.65 g of 4-acetoxystyrene and 36.55 g of CBCBS prepared above were added to the reactor, 0.98 g of AIBN was added thereto, stirred at a temperature of 40 ° C. for 30 minutes under a nitrogen atmosphere, and the temperature was raised to reflux the reaction solution. The reaction was stirred for 24 hours while maintaining it.

After the reaction was completed, the temperature was lowered to room temperature, and the reaction solution was immersed in 3 L of hexane to obtain a precipitate.

The precipitate obtained was filtered off, washed several times with 2 L of hexane and dried in vacuo.

The dried polymer was dissolved in 300 ml of methanol in a flask, stirred slowly by adding 50 ml of 30% NH ₄ OH aqueous solution, and further stirred for 30 minutes after the polymer was completely dissolved.

The solution was immersed in 1.5 L of water to obtain a precipitate, which was filtered, washed several times with 2 L of pure water and vacuum dried for 2 days to give 60.48 g of a poly (HS-co-CBCBS) polymer resin. .

The synthesis is according to Scheme 4 below.

Scheme 4

Examples 2-6

Chemically amplified resist compositions

Using poly (HS-co-CBCBS) represented by the formula (1a) prepared in Example 1 as an alkaline developing polymer resin,

[Formula 1a]

The compounds represented by the following Chemical Formulas 2, 3, 4, and 5 were dissolved in propylene glycol monomethyl ether acetate (PGMEA) in the composition shown in Table 1 using photoacid generators to obtain chemically amplified resist compositions.

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

The chemically amplified resist compositions were spun onto a silicon wafer at 2200 rpm and heated at 100 ° C. for 90 seconds to form a thin film of the thickness shown in Table 1.

A fine pattern mast was mounted on the thin film, irradiated with short wavelength light of 248 nm, and heated at 110 ° C. for 90 seconds to cause chemical amplification.

After developing for 60 seconds with an aqueous 2.38% tetramethylammonium hydroxide solution, the mixture was washed with pure water and dried to obtain a fine pattern on a wafer.

Table 1 shows the relative sensitivity and resolution of the fine pattern.

Comparative Examples 1 and 2

A chemically amplified resist composition was prepared in the same manner as in Example 1 using poly (hydroxystyrene) blocked with a tertiary-Butoxy Carbonyl (t-BOC) group represented by Chemical Formula 6 with the composition shown in Table 1 as a polymer resin, and then In the same manner as in Examples 2 to 6, a thin film was formed by spin coating and heating on a silicon wafer, and chemically amplified to obtain a fine pattern.

[Formula 6]

Table 1 shows the relative sensitivity and resolution of the fine pattern.

TABLE 1

division Resist composition Pattern properties Polymer (parts by weight) Photoacid Generator (parts by weight) Solvent (part by weight) Thin film thickness (㎛) Relative Sensitivity (mj / ㎠) Resolution (μm) Example 2 Formula 1a (100) Formula 2 (5) PGMEA (550) 0.70 28 0.24 Example 3 Formula 1a (100) Formula 3 (5) PGMEA (550) 0.72 32 0.22 Example 4 Formula 1a (100) Formula 4 (5) PGMEA (550) 0.72 24 0.20 Example 5 Formula 1a (100) Formula 5 (2) PGMEA (550) 0.70 33 0.20 Example 6 Formula 1a (100) Formula 5 (2) PGMEA (550) 0.70 38 0.26 Comparative Example 1 Formula 6 (100) Formula 2 (5) PGMEA (550) 0.74 58 0.48 Comparative Example 2 Formula 6 (100) Formula 3 (5) PGMEA (550) 0.72 52 0.45

* Relative sensitivity in Table 1 means optimal energy (Eop).

The chemically amplified resist composition including the polymer resin represented by Chemical Formula 1 of the present invention may form a fine pattern of excellent resolution on a wafer in response to a short wavelength in a photolithography process.

Claims (6)

(Correction) A polymer resin having a weight average molecular weight (Mw) represented by the following formula (1) of 3,000 to 30,000 and a dispersity of 1.01 to 3.00: [Formula 1] Where R ₁ is chlorine, bromo, hydroxy, cyano, t-butoxy, CH ₂ NH ₂ , CONH ₂ , CH = NH, CH (OH) NH ₂ or C (OH) = NH, R ₂ is hydrogen or methyl, x is 0.1-0.9. (delete) (Correction) a) 0.1 to 50% by weight of a polymer resin having a weight average molecular weight (Mw) represented by the following formula (1) is 3,000 to 30,000 and a dispersity of 1.01 to 3.00 [Formula 1] Where R ₁ is chlorine, bromo, hydroxy, cyano, t-butoxy, CH ₂ NH ₂ , CONH ₂ , CH = NH, CH (OH) NH ₂ or C (OH) = NH, R ₂ is hydrogen or methyl, x is 0.1 to 0.9; b) 0.1 to 50% by weight acid generator; And c) 0.1 to 99% by weight of solvent Photosensitive chemically amplified resist composition comprising a. (delete) (Correction) The method according to claim 3, The acid generator of b) , , , , , , , , , , , , , , Phosphorus sulfonium salts; , , , , Phosphorus iodonium salts; , , , Phosphorus N-iminosulfonates; (Wherein R is H, -CH ₃ or -C (CH ₃ ) ₃ ) disulfones; Bisarylsulfonyldiazomethanes wherein R is H, -CH ₃ or -C (CH ₃ ) ₃ ; (Wherein R is H, —CH ₃ or —C (CH ₃ ) ₃ ) A photosensitive chemically amplified resist composition selected from the group consisting of arylcarbonylarylsulfonyldiazomethanes. (Correction) The method according to claim 3, The solvent of c) is ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, ethyl ether acetate, n-butyl acetate, methyl isobutyl ketone, ethyl lactate, 3-ethoxy-ethylpropionate, 3- Methoxy-methylpropionate, diglycol monoethyl ether, 2-heptanone, diacetone alcohol, β-methoxyisobutyric acid methyl ester, propylene glycol monomethyl ether, propylene glycol monomethyl propionate, methyllac Photosensitive chemically amplified resist composition selected from the group consisting of tate, butyl lactate, ethyl pyruvate, and γ-butyrolactone.