KR100966397B1 - Photosensitive polymer for photoresist and manufacturing method thereof and photoresist composition comprising thereof - Google Patents

Abstract

The present invention relates to a photosensitive polymer for photoresists, a method for producing the same, and a photoresist composition containing the same. Concretely, the adhesion to the lower film is improved by -OH on the main chain including polyvinyl alcohol (PVA), the structure of the polyvinyl alcohol is simple, the interval between the main chains is narrow, The polymer is provided. In addition, since the PVA can not be produced by direct polymerization of a vinyl alcohol monomer, it provides a method for producing the photosensitive polymer through a saponification reaction of a polymer containing a vinyl ester repeating unit.

The photoresist composition containing the photosensitive polymer is excellent in adhesion to a lower film and in etching resistance and can be effectively used in a lithography process using a DUV excimer laser light source.

Photosensitive polymer, PVA, DUV excimer laser, adhesion, etch resistance

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive polymer for photoresists, a method for producing the same, and a photoresist composition containing the same.

The present invention relates to a photosensitive polymer for photoresists, a method for producing the same, and a photoresist composition containing the same. More specifically, the present invention relates to a photosensitive polymer containing polyvinyl alcohol and a method for producing the same, To a photoresist composition having excellent adhesion to a film.

BACKGROUND ART [0002] With the recent development of LSI (Large Scale Intergration) technology, semiconductor devices are becoming more integrated. As a result, the wavelength of the light source for lithography is shifted to a shorter wavelength in the g line or i line area used conventionally. Recently, KrF (248 nm) excimer laser and ArF (193 nm) excimer laser have been used as DUV (Deep UV) source. In particular, ArF excimer laser is the most popular light source in lithography requiring a pattern of the next generation of 0.01 micron or less.

In general, a photoresist composition for an ArF excimer laser should satisfy the following requirements. (ii) the glass transition temperature must be high; (iii) the etching resistance must be high; (iv) the adhesion to the film must be excellent; (v) It should be easy to develop with 2.38 wt% tetramethyl ammonium hydroxide (TMAH).

Particularly, as the pattern becomes finer, the adhesion with the lower film and the corrosion-resisting arousal are emphasized so as not to collapse the pattern. This is because the thickness of the photoresist layer is thin and the size of the pattern is small, so that the pattern collapse more easily due to the capillary force generated during the development process and the lack of adhesion to the lower film.

In addition, the photoresist should have a masking function so that it can occur not only in the pattern formation but also in a part of the silicon wafer after the pattern formation except for the part where the ion implanting or etching is covered with the photoresist. Therefore, etching resistance is required, and when the fine pattern is formed, the thickness of the photoresist layer becomes thinner, so that the etching resistance is further emphasized.

In order to solve the above problems, an object of the present invention is to provide a photosensitive polymer for a photoresist having strong attraction between molecules and excellent adhesion to a lower film, a process for producing the same, To provide a resist composition.

According to an aspect of the present invention,

There is provided a photoresist polymer for photoresists comprising a structure represented by the following formula (1): < EMI ID =

[Chemical Formula 1]

(In the formula 1,

R ₁ , R ₂ Is an alkyl group having 1 to 10 carbon atoms,

R ₃ Is a methyl group, an ethyl group or an isopropyl group,

X, y and z are mole% of each repeating unit with respect to all the repeating units constituting the photosensitive polymer, and are independently 1 to 60 mol%.

In Formula 1, z may be 10 to 40 mol% based on the total repeating units constituting the photosensitive polymer.

In another aspect of the present invention, there is provided a process for preparing a photosensitive polymer comprising saponifying a polymer containing a repeating unit represented by the following formula (2) with sodium hydroxide or potassium hydroxide:

(2)

(In the formula (2)

R ₁ , R ₂ and R ₄ are alkyl groups having 1 to 10 carbon atoms,

R ₃ is a methyl group, an ethyl group or an isopropyl group,

X, y and z are mole% of each repeating unit with respect to all the repeating units constituting the photosensitive polymer, and are independently 1 to 60 mol%.

According to another aspect of the present invention,

A photosensitive polymer comprising the structure of Formula 1; Photoacid generators; And a photoresist composition comprising an organic solvent.

The photosensitive polymer may be contained in an amount of 1 to 30 parts by weight based on 100 parts by weight of the total photoresist composition.

According to the production method of the present invention, it is possible to easily produce a photoresist photosensitive polymer containing poly vinyl alcohol which can not be obtained by polymerization of a monomer. The photosensitive polymer has a large adhesiveness to the lower film and an attractive force between the molecules.

The photoresist composition containing the photosensitive polymer has high etching resistance and is excellent in adhesion with the underlying film, so that the pattern can be prevented from collapsing and a uniform pattern can be formed after the etching process. Therefore, it can be advantageously used in a lithography process using a DUV excimer laser as a light source for fine pattern formation.

Hereinafter, the present invention will be described in detail.

The present invention provides a photosensitive polymer for a photoresist comprising a structure represented by the following general formula (1)

[Chemical Formula 1]

(In the formula 1,

R ₁ and R ₂ are alkyl groups having 1 to 10 carbon atoms,

R ₃ is a methyl group, an ethyl group or an isopropyl group,

X, y and z are mole% of each repeating unit with respect to all the repeating units constituting the photosensitive polymer, and are independently 1 to 60 mol%.

The photosensitive polymer for photoresist containing the structure represented by the above formula (1) contains polyvinyl alcohol containing -OH, and when used in a photoresist composition, not only the adhesion to the lower film is good, but also the hydrogen bond increases, Can be prevented from being collapsed, and the etching resistance is also improved.

Conventionally, a polymer containing a structure represented by the following formula (3) has been used as a DUV photoresist:

(3)

(3)

and n is 1 to 60 mol% based on the total repeating units of the photosensitive polymer.

The structure of Formula 3 enhances the adhesion to the underlying film by -OH, and the relatively weak etch resistance compensates for the adamantane group occupying a large volume. However, since -OH is attached to a bulky side branch, the adhesive strength to the lower film is relatively weaker than that of the side chain, and due to the bulky side branch, the distance between the main chains is widened, If the thickness is low, it may cause collapse of the pattern. Also, the etching resistance is reduced.

In the photosensitive polymer having the structure represented by Formula 1, -OH, which is a hydrophilic functional group, is attached to the main chain and thus has a relatively strong adhesion to the lower layer. The polyvinyl alcohol contained in the photosensitive polymer is narrow in structure and small in volume so that the interval between chains is narrowed. Therefore, attraction and hydrogen bonding between molecules can be prevented to prevent pattern collapse, and etching resistance is also increased.

The photosensitive polymer having the structure of Formula 1 may be a block copolymer or a random copolymer, and preferably has a weight average molecular weight (Mw) of 3,000 to 100,000.

According to an embodiment of the present invention, z in Formula 1 may be 10 to 40 mol% based on the total repeating units of the photosensitive polymer. When the content is less than 10 mol%, the content of polyvinyl alcohol is too small and the adhesiveness to the lower film and the etching resistance are poor. When the content exceeds 40 mol%, the bonding force with the lower film is strengthened, but the hydrogen bonding of polyvinyl alcohol is too strong There is a problem that the photoresist of the exposed portion is not washed away during the developing process.

The present invention provides a process for preparing a photosensitive polymer for photoresists comprising the structure of Formula 1.

The photoresist photosensitive polymer containing the structure of Formula 1 may be prepared by saponifying a polymer containing a repeating unit represented by Formula 2 with sodium hydroxide or potassium hydroxide.

(2)

(In the formula (2)

R ₁ , R ₂ and R ₄ are alkyl groups having 1 to 10 carbon atoms,

R ₃ is a methyl group, an ethyl group or an isopropyl group,

X, y and z are mole% of each repeating unit with respect to all the repeating units constituting the photosensitive polymer, and are independently 1 to 60 mol%.

Since the vinyl alcohol, which is a monomer of polyvinyl alcohol, is converted into an enol-keto tautomerism and converted to an aldehyde, its presence is impossible and polyvinyl alcohol can not be obtained by direct polymerization of monomers. By the above production method, a photosensitive polymer containing polyvinyl alcohol which can not be obtained by direct polymerization of monomers can be produced.

First, a vinyl ester-based precursor is polymerized to obtain a polymer containing a repeating unit of the above formula (2). Specific examples of vinyl ester-based precursors include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl trichloroacetate, vinyl trifluoroacetate, , Vinyl pivalate, and the like.

Next, the polymer containing the repeating unit represented by the above formula (2) is subjected to a saponification reaction with sodium hydroxide or potassium hydroxide to obtain a photosensitive polymer containing polyvinyl alcohol.

A process for synthesizing a polymer having the structure of the formula (1) from the vinyl ester-based precursor is shown in FIG.

The present invention provides a photosensitive polymer comprising the structure of Formula 1; Photoacid generators; And a photoresist composition comprising an organic solvent.

Since it includes the photosensitive polymer having the structure of Formula 1, it has excellent adhesion to the lower film, which can prevent the collapse of the pattern and is also excellent in etching resistance. Therefore, the present invention can also be advantageously used when a DUV excimer laser is used as a light source to form a fine pattern.

According to an embodiment of the present invention, the photosensitive polymer having the structure of Formula 1 may be contained in an amount of 1 to 30 parts by weight based on 100 parts by weight of the total photoresist composition. If the content of the photosensitive polymer containing the structure of the formula (1) is less than 1 part by weight, the coating layer is too thin to obtain the expected acid-proliferating effect and the etching resistance is reduced. If added in excess of the above range, the uniformity of the coating is lowered.

The photoacid generator generates an acid component such as H ⁺ by exposure to induce a chemical amplification action.

The photoacid generator may be any compound capable of generating an acid by light, and may be any of the onium salts such as iodonium salts, sulfonium salts, phosphonium salts, diazonium salts, And the like. Non-limiting examples of photoacid generators include phthalimidotrifluoromethane sulfonate, dinitrobenzyltosylate, n-decyldisulfone, naphthylimidotrifluoromethanesulfonate, dipetyl There may be mentioned, for example, iodonium hexafluorophosphate, diphenyliodonium hexafluoroarsenate, diphenyliodonium hexafluoroantimonate, diphenyl para-toluenesulfonium triflate, triphenylsulfonium hexafluoroantimonate, Triphenylsulfonium triflate, dibutylnaphthylsulfonium triflate, and mixtures thereof.

In order to obtain a uniform and flat photoresist film, the photoresist composition is used by dissolving it in an organic solvent having an appropriate evaporation rate and viscosity.

Examples of the organic solvent include ethylene glycol monomethyl ether, ethylene glycol monopropyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, mail isopropyl ketone, cyclohexanone, methyl 2-hydroxypropionate, Ethyl 2-hydroxypropionate, 2-heptanone, ethyl lactate, and? -Butyrolactone, or a mixture thereof.

Hereinafter, the present invention will be described with reference to examples and comparative examples. It is a preferred embodiment of the present invention, and the scope of the present invention is not limited thereto.

< Example  1> Preparation of Photosensitive Polymer

1-1. 5 g of a polymer in which R ₁ , R ₂ , R ₃ and R ₄ are CH ₃ and x, y and z are respectively 30 mol%, 40 mol% and 30 mol% in the above-mentioned formula 2 are dissolved in THF (tetrahydrofuran) Dissolved in 20 g of solvent. 0.02 mol of sodium hydroxide and 0.05 mol of water is injected into the solvent in which the photosensitive polymer is dissolved at a rate of 60 droplets / min for 1 minute. The temperature was maintained at 40 占 폚, and after 3 hours, it was precipitated in ether to prepare a powdery photosensitive polymer.

1-2. Except that 5 g of a polymer in which R ₁ , R ₂ , R ₃ and R ₄ are CH ₃ and x, y and z are 30 mol%, 30 mol% and 40 mol%, respectively, A photosensitive polymer was prepared in the same manner as in Example 1-1.

1-3. Except that 5 g of a polymer in which R ₁ , R ₂ , R ₃ and R ₄ are CH ₃ and x, y and z are 30 mol%, 60 mol% and 10 mol%, respectively, A photosensitive polymer was prepared in the same manner as in Example 1-1.

Table 1 shows the physical properties of the photosensitive polymer prepared in Examples 1-1 to 1-3.

[Table 1]

Mw PDI yield(%) Example 1-1 8800 1.78 72 Examples 1-2 7600 1.69 69 Example 1-3 9200 1.83 74

< Example  2> Photoresist  Composition manufacturing

2-1. 2.0 g of the photosensitive polymer prepared in Example 1-1 and 0.02 g of triphenylsulfonium triflate (TPS-105) were completely dissolved in 20 g of propylene glycol monomethyl ether acetate (PGMEA) To obtain a photoresist composition.

2-2. A photoresist composition was obtained in the same manner as in Example 2-1, except that 2.0 g of the photosensitive polymer prepared in Example 1-2 was used.

2-3. A photoresist composition was obtained in the same manner as in Example 2-1, except that 2.0 g of the photosensitive polymer prepared in Example 1-3 was used.

< Comparative Example  1> PVA Not including Photoresist  Preparation of composition

In Example 2-1, a photoresist composition was prepared in the same manner as in Example 2-1, except that 2.0 g of the photosensitive polymer of Formula 4 was used instead of 2.0 g of the photosensitive polymer of Example 1-1. Were prepared:

[Chemical Formula 4]

(In the formula 4,

X, y and z are molar percentages of the respective repeating units with respect to the total repeating units constituting the photosensitive polymer, which are 30 mol%, 40 mol% and 30 mol%, respectively.

< Experimental Example  1> Identification of Photosensitive Polymers

IR was measured to confirm the functional groups of the photosensitive polymer prepared in Examples 1-1 to 1-3. The results are shown in Fig. Referring to FIG. 2, peaks corresponding to -OH functional groups were observed in all of the photosensitive polymers prepared in Examples 1-1 to 1-3, indicating that a polymer having -OH functional groups was prepared.

< Experimental Example  2> Photoresist  Pattern formation

The photoresist composition prepared in Example 2 and Comparative Example 1 was coated on the upper surface of a SiO ₂ film on a silicon wafer treated with hexamethyldisilazoxide (HMDS) to a thickness of about 0.2 μm. The wafer coated with the photoresist composition was prebaked at 100 캜 for 90 seconds, exposed using an ArF excimer laser with a numerical aperture of 0.6, and then subjected to PEB (post exposure baking) at 120 캜 for 90 seconds. And developed with 2.38 wt% TMAH solution for 30 seconds to obtain a line and space pattern of 0.1 mu m.

< Experimental Example  3> Etching process

The SiO ₂ film was etched using a mixed gas of carbon tetrafluoride (CF ₄ ) and argon (Ar) using the photoresist pattern formed in Experimental Example 1 as an etching mask.

< Experimental Example  4> Adhesive strength measurement

The number of peeling dots per unit area of the photoresist pattern formed using the photoresist composition prepared in Example 2 and Comparative Example 1 was counted to measure the adhesive strength. The results are shown in Table 2.

[Table 2]

Number of filling dots / 100㎠ Example 2-1 0 Example 2-1 0 Example 2-3 One Comparative Example 1 7

As shown in Table 2, the photoresist pattern formed using the photoresist composition of Example 2 showed almost no peeling dot, and no pattern collapse was observed at the time of pattern formation, indicating that the adhesion with the lower film was improved . As the content of the polyvinyl alcohol repeating unit increases, the adhesion to the lower film is improved.

< Experimental Example  4> Etching  tolerance

The thickness of the remaining photoresist layer after the etching process of Experimental Example 3 was measured by an electron microscope. The thickness of the photoresist layer of the comparative example is assumed to be 1, and the relative value of the thickness of the photoresist layer of the embodiment is taken as etching resistance. The results are shown in Fig.

Referring to FIG. 3, the etching resistance of the example was improved compared with the comparative example, and the etching resistance was the highest when the polyvinyl alcohol content was 40 mol%. However, if the content of polyvinyl alcohol is increased to increase the etching resistance, the pattern may not be removed cleanly during the developing process as described above.

As a result, the photoresist composition of the present invention can be advantageously used in a lithography process using a DUV excimer laser to form a fine pattern with improved adhesiveness to a lower film and etching resistance.

1 shows a method for producing a photosensitive polymer according to an embodiment of the present invention.

2 shows IR results of the photosensitive polymer prepared according to one embodiment of the present invention.

FIG. 3 shows the result of measuring the etching resistance after the etching process.

Claims (5)

A photoresist photosensitive polymer comprising a structure represented by the following formula (1): &lt; EMI ID = [Chemical Formula 1]

(In the formula 1, R ₁ and R ₂ are alkyl groups having 1 to 10 carbon atoms, R ₃ is a methyl group, an ethyl group or an isopropyl group, X, y and z are mole% of each repeating unit with respect to all the repeating units constituting the photosensitive polymer, and are independently 1 to 60 mol%. The method according to claim 1, Wherein z is from 10 to 40 mol% based on the total repeating units of the photosensitive polymer. A process for producing a photoresist photosensitive polymer according to any one of claims 1 to 3, which comprises saponifying a polymer containing a repeating unit represented by the following formula (2) with sodium hydroxide or potassium hydroxide: (2)

(In the formula (2) R ₁ , R ₂ and R ₄ are alkyl groups having 1 to 10 carbon atoms R ₃ is a methyl group, an ethyl group or an isopropyl group, X, y and z are mole% of each repeating unit with respect to all the repeating units constituting the photosensitive polymer, and are independently 1 to 60 mol%. The photosensitive polymer of claim 1 or 2; Photoacid generators; And Wherein the photoresist composition comprises an organic solvent. 5. The method of claim 4, Wherein the photosensitive polymer is contained in an amount of 1 to 30 parts by weight based on 100 parts by weight of the total photoresist composition.

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