KR20010011604A - Silicon-containing Photoresist Composition - Google Patents

Abstract

PURPOSE: A photoresist composition comprising a polymer and a photoacid generator is provided, which is suitable for a bilayer process and has high thermal stability causing no decomposition even at a temperature higher than glass transition temperature and improved wettability to a developing solution and adhesion to a substrate. CONSTITUTION: This photoresist composition comprises a polymer of formula 1 having a weight average molecular weight of 3,000 to 50,000 and 1 to 15% by weight of a photoacid generator based on the polymer. The photoresist can further contain 0.01 to 2.0% by weight of an organic base based on the weight of the polymer. In formula, R1 is H or methyl; R2 is H or a C1-4 hydrocarbon compound. w, x, y, z are all an integer; w/(w+x+y+z) is 0.1 to 0.5; x/(w+x+y+z) is 0.5 to 0.7; y/(w+x+y+z) is 0.0 to 0.2 and z/(w+x+y+z) is 0.0 to 0.3.

Description

Silicon-containing Photoresist Composition

The present invention relates to materials for the manufacture of semiconductor devices, and more particularly to photoresist compositions.

As the semiconductor manufacturing process becomes complicated and the degree of integration increases, the formation of fine patterns according to the design rule of 0.25 μm is urgently required. In accordance with the demand for miniaturization of such a pattern, the exposure source is also changed with an ArF excimer laser (193 nm) that uses a light wavelength of a shorter wavelength region than that of a conventional DUV (deep UV: 248 nm). Therefore, there is also a need for a new photoresist material capable of operating at 193 nm, the wavelength region of the ArF excimer laser.

However, when the photoresist pattern is formed for the photolithography process, as the photoresist pattern becomes finer, dry etch resistance may not be sufficiently secured, and the pattern collapse due to an increase in aspect ratio is more frequent. Occurs. Therefore, a photolithography method using a conventional photoresist pattern could not form a material layer pattern having a good profile.

Recently, a bi-layer process has been proposed to prevent this phenomenon. The double layer process is a process of performing a photolithography process using a photoresist containing silicon, wherein a silicon layer in the photoresist pattern is formed into glass during dry etching by plasma to form a cured layer on the surface of the photoresist pattern. The principle is to use. When the cured layer is formed in this way, not only the dry etching resistance may be increased, but also the pattern may be prevented from falling down.

On the other hand, in the case of silicon-containing photoresist, there is a problem in that the thermal stability and the wettability to the developer is lowered as the silicon content increases. Therefore, there is an urgent need for the development of a photoresist including a ratio of silicon suitable for a double film process, and having high thermal stability and high wettability to a developer.

The technical problem to be achieved by the present invention is to provide a photoresist composition suitable for a double film process, high thermal stability and wettability to the developer.

The photoresist composition according to the present invention for achieving the above technical problem is composed of a polymer represented by the following formula (1) and a photoacid generator of 1 to 15% by weight based on the weight of the polymer.

The photoacid generator is preferably a triarylsulfonium salt, a diaryl iodonium salt or a sulfonium salt.

The photoresist composition preferably further comprises an organic base.

Wherein R ₁ is hydrogen or a methyl group,

R ₂ is hydrogen or a hydrocarbon compound having 1 to 4 carbon atoms,

w, x, y, z are all integers, w / (w + x + y + z) is 0.1-0.5, x / (w + x + y + z) is 0.5-0.7, y / (w + x + y + z) is 0.0-0.2, z / (w + x + y + z) is 0.0-0.3 and the weight average molecular weight of the polymer is 3,000-50,000.

Forming a photoresist pattern with the photoresist composition of the present invention increases the etching resistance of the photoresist pattern and prevents the pattern from falling down. In addition, the thermal stability is high, the wettability to the developer and good adhesion to the substrate.

Hereinafter, a polymer according to the present invention and a photoresist composition comprising the same will be described. Moreover, the preferable photolithography process using a photoresist composition is also demonstrated. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you.

Photoresist Polymers and Photoresist Compositions

The photoresist polymer constituting the photoresist composition according to the present invention is represented by the following formula (1).

[Formula 1]

Wherein R ₁ is hydrogen or a methyl group,

R ₂ is hydrogen or a hydrocarbon compound having 1 to 4 carbon atoms,

w, x, y, z are all integers, w / (w + x + y + z) is 0.1-0.5, x / (w + x + y + z) is 0.5-0.7, y / (w + x + y + z) is 0.0-0.2, z / (w + x + y + z) is 0.0-0.3 and the weight average molecular weight of the polymer is 3,000-50,000.

Preferably the weight average molecular weight of the polymer is from 5,000 to 30,000.

And R ₂ in the polymer is preferably a methyl, ethyl, 2-hydroxyethyl or 2-aminoethyl group.

The photoresist composition according to the present invention comprises a photoacid generator mixed with the polymer of Formula 1 and 1 to 15% by weight based on the weight of these polymers.

As the photoacid generator, a material having high thermal stability is preferably used. Thus, triarylsulfonium salts, diaryliodonium salts or sulfonates can be used. For example, triphenylsulfonium triflate, triphenylsulfonium antimonate, diphenyliodonium triflate, diphenylidonium antimonate, methoxydi Methoxydiphenyliodonium triflate, di-t-butyldiphenyliodonium triflate, 2,6-dinitrobenzyl sulfonate, fatigue Pyrogallol tris (alkylsulfonates), or N-hydroxysuccinimide triflate may be used as the photoacid generator.

The photoresist composition according to the present invention further comprises 0.01 to 2.0% by weight of organic base based on the weight of the polymer. Triethylamine, triisobutylamine, triisooctylamine, diethanolamine or triethanolamine are used as the organic base. After exposure, the organic base is added to prevent the problem that the acid generated in the exposed portion diffuses into the non-exposed portion to form a non-exposed portion, which also hydrolyzes and deforms the pattern.

The polymer constituting the photoresist composition according to the present invention comprises a silicon atom, is composed of norbornane having a cyclic structure in the skeleton, a hydroxyl group is bonded as a functional group, and maleic anhydride having high polarity as a component. Have Therefore, it can be applied to the double membrane process, it has high etching resistance, excellent adhesion to the underlying film quality, and excellent wettability to the developer. In addition, since it has a bulky state before exposure but has maleic anhydride and (meth) acrylic acid derivative which is an ester compound which forms a carboxyl group by the acid which generate | occur | produced by exposure, as a component, the polarity and non-exposure of the photoresist film of the exposed part are carried out. The polarity of the photoresist film in the portion where the portion is markedly differs and the contrast is greatly increased. In addition, the composition according to the present invention includes a thermally stable polymer and a photoacid generator and thus has thermal stability that does not decompose even at a temperature above the glass transition temperature.

Method of Making Polymers

1. Manufacturing method of monomer (II)

As in Scheme 1, 5-norbornene-2,3-dicarboxylate anhydride (I) is treated with a reducing agent such as lithium aluminum hydride to reduce anhydride to alcohol to prepare monomer (II).

2.Production method of monomer (III)

As in Scheme (2) below, monomer (III) is prepared through a substitution reaction between monomer (II) synthesized above and an alkyl halide silane such as trimethylsilane.

3. Manufacturing method of polymer

The monomers (II) and (III) prepared above and maleic anhydride (IV) and (meth) acrylic acid derivatives (V) prepared as in Scheme 3 below are dissolved in an organic solvent such as toluene or tetrahydrofuran (THF). After the polymerization, a polymerization initiator such as azobisisobutyronitrile (AIBN) is added to the polymerization reaction to prepare the polymer (VI) represented by Chemical Formula 1.

Wherein R ₁ is hydrogen or a methyl group,

R ₂ is hydrogen or a hydrocarbon compound having 1 to 4 carbon atoms,

w, x, y, z are all integers, w / (w + x + y + z) is 0.1-0.5, x / (w + x + y + z) is 0.5-0.7, y / (w + x + y + z) is 0.0-0.2, z / (w + x + y + z) is 0.0-0.3 and the weight average molecular weight of the polymer is 3,000-50,000.

Manufacturing method of photoresist composition and photolithography method using same

A photoresist composition is prepared by dissolving 1 to 15% by weight of a photoacid generator in a suitable solvent to a polymer (VI) represented by Chemical Formula 1 in a suitable solvent. As the photoacid generator, the triarylsulfonium salt, the diaryl iodonium salt or the sulfonium salt (sulfonates) described above are used. Further, an organic base which is 0.01 to 2.0% by weight based on the weight of the polymer is further added.

The photolithography process using the photoresist composition prepared according to the method described above proceeds as follows.

First, hexamethyldisilazane (HMDS) is applied onto a substrate on which a target layer to be patterned is formed, and then the photoresist composition described above is applied to form a photoresist film having a predetermined thickness. The polymer constituting the photoresist composition according to the present invention contains a large amount of hydroxy groups and maleic anhydride with high polarity and thus easily adheres to the substrate. Next, pre-baking is performed on the photoresist film. After the pre-exposure bake step, the photoresist film is exposed using a mask in which a predetermined pattern is formed using an ArF excimer laser as the exposure source. By exposure, an acid is generated from the photoacid generator in the photoresist film, and the generated acid catalyzes to hydrolyze the polymer as shown in Scheme 4 to form a large amount of carboxy groups.

Therefore, the polarity of the photoresist film of the exposed portion and the polarity of the photoresist film of the unexposed portion are remarkably different. In other words, the contrast is significantly increased.

After the exposure is completed, before the development, the photoresist film is heat-treated again for a short time (post-exposure-thermal treatment). The post-exposure heat treatment is performed to further activate the acidolysis reaction by the acid catalyst in the exposed portion. In other words, it is carried out to increase the contrast by hydrolyzing both the siloxy and ester groups of the polymer in the exposed portion to alcohol and carboxy groups.

Next, a developing step is performed using an appropriate developer to complete the photoresist pattern. As described above, the photoresist composition constituting the photoresist pattern has a good wettability to a developer, so that a developing process occurs smoothly. At this time, the developer used is a developer at a concentration used in a conventional process, such as 2.38% by weight of TMAH.

When the etching target layer under the photoresist pattern is etched using the thus formed photoresist pattern, silicon atoms in the photoresist pattern are vitrified to form a cured layer on the surface of the photoresist pattern, and the cured layer thus formed is etched in the photoresist pattern. In addition to increasing resistance, the pattern can also be prevented from falling down.

The present invention is described in more detail with reference to the following experimental examples, which are not intended to limit the present invention.

Experimental Example 1: Preparation of 5-norbornene-2,3-dimethanol

Lithium aluminum hydride (0.25 mol) was dissolved in anhydrous tetrahydrofuran (600 ml) in a round neck flask. 5-norbornene-2,3-dicarboxylic anhydride (0.2 mol) was slowly added thereto, followed by reaction at room temperature for about 12 hours.

After the reaction was completed, excess solvent was removed, the reaction was poured into excess water, neutralized with hydrochloric acid, extracted with diethyl ether, dried over magnesium sulfate, and the reaction product was separated using vacuum distillation. (Yield 75%).

Experimental Example 2: Silaneization of 5-norbornene-2,3-dimethanol

In a round neck flask, 5-norbornene-2,3-dimethanol (0.1 mole) was dissolved in methylene chloride (250 ml) together with triethylamine (0.25 mole), and then trimethylsilane (0.25 mole) was slowly dropped therein. After the reaction was carried out at room temperature for about 12 hours.

Subsequent steps were carried out in the same manner as in Experiment 1 to separate the reaction product. (Yield 80%).

Experimental Example 3: Preparation of Binary Copolymer

15 g of the monomer (50 mmol) synthesized in Experimental Example 2 and 4.9 g of maleic anhydride (50 mmol) were dissolved in dioxane anhydride (40 ml) together with 0.16 g of AIBN, a polymerization initiator, and then purged with nitrogen gas for about 1 hour. The polymerization was then carried out at a temperature of 65 ° C. for about 24 hours.

After the completion of the polymerization, the reactant was precipitated by slowly dropping the excess in n-hexane, and then the precipitate was dissolved in THF (tetrahydrofuran) again, and again precipitated in n-hexane to obtain a precipitate. The precipitate obtained was dried in a vacuum oven maintained at about 50 ° C. for about 24 hours to separate the reaction product.

The obtained reaction product was a binary copolymer with a weight average molecular weight of 11,700 and a polydispersity of 1.8.

Experimental Example 4: Preparation of Ternary Copolymer

0.8 g of the monomer (5 mmol) prepared in Experimental Example 1, 13.5 g of the monomer (45 mmol) prepared in Experiment 2 and 4.9 g of maleic anhydride (50 mmol) were combined with 0.16 g of AIBN (40 ml). Dissolved in. The copolymer was synthesized and separated in the same manner as in Experimental Example 3.

The obtained polymer was a ternary copolymer with a weight average molecular weight of 12,800 and a polydispersity of 2.0.

Experimental Example 5: Preparation of Ternary Copolymer

12 g of the monomer (40 mmol) prepared in Experimental Example 2, 1.2 g of 2-hydroxyethyl acrylic acid (10 mmol) and 4.9 g of maleic anhydride (50 mmol) were dissolved in dioxane anhydride (40 mL) together with 0.16 g of AIBN. I was. The copolymer was synthesized and separated in the same manner as in Experimental Example 3.

The obtained polymer was a ternary copolymer with a weight average molecular weight of 10,800 and a polydispersity of 1.87.

Experimental Example 6: Preparation of Ternary Copolymer

A copolymer was synthesized and separated in the same manner as in Experiment 5, except that 1.0 g of methyl methacrylic acid (10 mmol) was used instead of 2-hydroxyethyl acrylic acid (10 mmol).

The obtained polymer was a ternary copolymer with a weight average molecular weight of 11,400 and a polydispersity of 2.1.

Experimental Example 7: Preparation of Quaternary Copolymer

0.8 g of the monomer (5 mmol) prepared in Experimental Example 1, 13.5 g of the monomer (45 mmol) prepared in Experiment 2, 4.9 g of maleic anhydride (50 mmol) and 0.58 g of 2-hydroxyethyl acrylic acid (5 mmol) Using to synthesize a copolymer in the same manner as in Experimental Example 3 was separated.

The polymer obtained was a four-way copolymer with a weight average molecular weight of 12,500 and a polydispersity of 2.0.

Experimental Example 8: Preparation of Photoresist Composition and Photolithography Process Using the Same

1.0 g of the binary copolymer (weight average molecular weight 12000) synthesized in Experimental Example 3 together with 0.02 g of triphenylsulfonium triflate (TPSOTf), a photoacid generator, was used. PGMEA) was dissolved in 8 g, and filtered using a 0.2 μm filter to obtain a photoresist composition.

After HMDS was processed on the wafer on which the material layer to be patterned was formed, the obtained photoresist composition was spin coated to a thickness of about 0.3 μm. After soft-baking the wafer coated with the photoresist composition at a temperature of about 120 ° C. for about 90 seconds, a mask having a desired pattern and a stepper using a KrF excimer laser having a numerical aperture (NA) of 0.45 were used. After exposure, post baking was carried out at a temperature of about 130 ° C. for about 90 seconds. Thereafter, it was developed for about 60 seconds with a 2.38 wt% tetramethylammonium hydroxide (TMAH) solution to form a photoresist pattern.

As a result, a photoresist pattern having a line width of 0.50 µm could be formed with an exposure energy of 17 mJ / cm 2 dose. The material layer was etched using the thus formed photoresist pattern. The collapse of the photoresist pattern was not found, and the etching resistance was also increased to form a material layer pattern having a desired critical dimension, that is, a material layer pattern having an excellent pattern profile.

Experimental Example 9: Preparation of Photoresist Composition and Photolithography Process Using the Same

Photoresist composition was prepared in the same manner as in Experiment 8 except that 1.0 g of the terpolymer (synthetic weight average molecular weight 13,000) synthesized in Experiment 4 was used and 2 mg of triethanolamine was added as an organic base. The process was carried out.

As a result, a photoresist pattern having a line width of 0.40 탆 could be formed with an exposure energy of 26 mJ / cm 2 dose.

Experimental Example 10 Preparation of Photoresist Composition and Photolithographic Etching Process Using the Same

Except that 1.0 g of the terpolymer (weight average molecular weight 11000) synthesized in Experimental Example 5 was used as a polymer and 2 mg of triisobutylamine was used instead of triethanolamine as an organic base to prepare a photoresist composition. In the same manner as in Experiment 8, a photoresist composition was prepared and a photolithography process was performed.

As a result, a photoresist pattern having a line width of 0.30 µm could be formed with an exposure energy of 23 mJ / cm 2 dose.

Experimental Example 11: Preparation of Photoresist Composition and Photolithographic Etching Process Using the Same

A photoresist composition was prepared in the same manner as in Experiment 9 except that 0.02 g of N-hydroxysuccinimide triflate was used instead of TPSOTf as a photoacid generator.

As a result, a photoresist pattern having a line width of 0.30 µm could be formed with an exposure energy of 31 mJ / cm 2 dose.

Experimental Example 12 Preparation of Photoresist Composition and Photolithographic Etching Process Using the Same

A photoresist composition was prepared in the same manner as Experimental Example 8 except that 1 g of a tetrapolymer (weight average molecular weight 12,500) synthesized in Experimental Example 7 was used and a photolithography process was performed.

As a result, a photoresist pattern having a 0.4 µm line width could be formed with an exposure energy of 13 mJ / cm 2 dose.

The photoresist polymer according to the present invention contains silicon atoms. Therefore, the photoresist composition prepared using these polymers may be suitable for the bi-layer process in the photolithography process to form a material layer pattern having a good profile. That is, after the photoresist pattern is formed with the photoresist composition according to the present invention, and the dry etching is performed, silicon atoms in the photoresist pattern are vitrified to form a cured layer on the surface of the photoresist pattern. It not only increases the etching resistance of the pattern, but also prevents the pattern from falling. Thus, the material layer pattern having a good profile can be formed to increase the efficiency of the photolithography process. In addition, the polymer constituting the photoresist composition according to the present invention is composed of norbornane whose skeleton is a cyclic structure, a hydroxyl group is bonded as a functional group, and has a polar polar maleic anhydride as a component. Therefore, the etching resistance is not only high, but also excellent adhesion to the lower film quality and excellent wettability to the developer. In addition, since it has a bulky state before exposure but has maleic anhydride and (meth) acrylic acid derivative which is an ester compound which forms a carboxyl group by the acid which generate | occur | produced by exposure, as a component, the polarity and non-exposure of the photoresist film of the exposed part are carried out. The polarity of the photoresist film in the portion where the portion is markedly differs and the contrast is greatly increased. In addition, the composition according to the present invention includes a thermally stable polymer and a photoacid generator and thus has thermal stability that does not decompose even at a temperature above the glass transition temperature.

Claims (3)

A polymer represented by the formula: A photoresist composition comprising 1 to 15% by weight of a photoacid generator based on the weight of the polymer. Wherein R ₁ is hydrogen or a methyl group, R ₂ is hydrogen or a hydrocarbon compound having 1 to 4 carbon atoms, w, x, y, z are all integers, w / (w + x + y + z) is 0.1-0.5, x / (w + x + y + z) is 0.5-0.7, y / (w + x + y + z) is 0.0-0.2, z / (w + x + y + z) is 0.0-0.3 and the weight average molecular weight of the polymer is 3,000-50,000. The photoresist composition of claim 1, wherein the photoacid generator is a triarylsulfonium salt, a diarylyodonium salt, or a sulfonium salt. The photoresist composition of claim 1, wherein the photoresist composition further comprises 0.01 to 2.0% by weight of an organic base based on the weight of the polymer.