KR20070002602A - Hard mask composition and pattern forming method using the same - Google Patents

Abstract

A hard mask composition for ultrafine patterning lithographic photoresist is provided to replace conventional two layers of BARC(bottom anti-reflective coating) and SiON(silicon oxynitride) layer, or three layers of BARC, SiON and amorphous carbon in ultrafine patterning process of lithographic photoresist using 193 nm ArF light source. The hard composition comprises: [2-(3,4-epoxycyclohexyl)ethyl]-heptaisobutyl substituted-PSS(polyhedral silsesquioxane) compound having molecular weight of 300 to 30,000 represented by a formula(1) wherein: R1 to R7 are hydrogen, substituted or non-substituted linear or branched C1-C5 alkyl group, substituted non-substituted C3-C8 cycloalkyl group, or substituted or non-substituted C5-C12 aromatic group; and x and y are integer ranging from 1 to 100; another compound having molecular weight of 500 to 50,000 represented by the formula(2); and a hot acid generator. Amount of the compound represented by the formula(1) ranges from 30 to 70wt. parts relative to 100wt. parts of the composition.

Description

Composition for hard mask and pattern formation method using the same {HARD MASK COMPOSITION AND PATTERN FORMING METHOD USING THE SAME}

1 is a schematic diagram of a conventional hardmask process drawing,

2 is a schematic diagram of a two-layer replacement hardmask process diagram of the present invention;

3 is a schematic diagram of a three-layer replacement hardmask process diagram of the present invention;

4 is an electron micrograph showing a photoresist pattern according to Example 2 of the present invention.

5 is an electron micrograph showing a hard mask pattern after etching according to Example 3 of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: Organic Antireflection Layer 2: SiON Hard Mask Layer

3: amorphous carbon hard mask layer 4: etching layer

5: photoresist pattern 12: hardmask layer of the present invention

The present invention is to replace the existing two layers of BARC and SiON, or three layers of BARC, SiON, and amorphous carbon in the process of forming a micro pattern of the photoresist for lithography mainly using a 193 nm ArF light source during the semiconductor device manufacturing process It relates to a composition for a hard mask and a pattern forming method using the same.

The bottom anti-reflective coating (BARC) used in the pattern formation process of the photoresist for lithography during the semiconductor device manufacturing process prevents diffuse reflection from the bottom layer and removes standing waves due to the thickness change of the photoresist layer itself. It has acted as an antireflective layer to increase the uniformity of the resist.

On the other hand, as the device becomes more and more fine, the thickness of the photoresist layer is also rapidly decreasing to prevent the photoresist pattern from falling down. Accordingly, the etching rate when the organic antireflection layer is etched by using the photoresist pattern as an etching mask. Various polymers and crosslinking agents for organic antireflective layers have been developed so that the organic antireflective layer can be easily removed by increasing.

Nevertheless, conventionally, in the photolithography process in consideration of the etching selectivity problem of the hard mask on the etched layer (4) above; Amorphous carbon hardmask layer 3; A SiON hardmask layer 2 and an organic antireflection layer 1 having a preferred etching selectivity relative to the amorphous carbon hardmask layer 3; And a complex multilayer structure in which the photoresist pattern 5 is sequentially formed (see FIG. 1).

Therefore, there is a need to simplify the process by developing a material having a lower etching selectivity compared to amorphous carbon while serving as an existing organic antireflection layer.

In order to develop such a material, it is first necessary to effectively replace the conventional organic antireflective layer, and the composition for forming the organic antireflective layer must satisfy the following requirements:

(1) After coating the antireflection layer, in the step of coating the photoresist layer thereon, the antireflection layer should not be dissolved by an organic solvent in the photoresist composition. To this end, in the process of coating the antireflective layer composition, baking and laminating the antireflective layer, the antireflective layer should be designed to have a crosslinked structure, and other chemicals should not be generated as by-products.

(2) In order to suppress the diffuse reflection from the underlying layer, it should contain a substance with absorbance in the wavelength band of the exposure light source.

(3) Finally, in the step of laminating the antireflection layer composition, a catalyst for activating the crosslinking reaction should be contained.

In addition, even if the above conditions are satisfied, in order to effectively replace the conventional organic antireflection layer, it is important to secure an etching selectivity for the material of the lower layer such as amorphous carbon.

Accordingly, an object of the present invention is to improve the uniformity of the pattern formed in the lithography process during the semiconductor device manufacturing process and to improve the etching selectivity. The present invention provides a hard mask composition having an etching selectivity and maintaining a very small etching selectivity compared to an amorphous carbon layer as a lower layer.

In addition, another object of the present invention is to provide a method for manufacturing a semiconductor device, the process of which is simplified by using the composition.

In order to achieve the above object, the present invention is a silicone-based crosslinking agent of the formula (1); Novolac (NOVOLAC) resin of the formula (2); Thermal acid generators; menstruum; Optionally a compound of formula 3; And optionally a photomask generator comprising:

Wherein R ₁ to R ₇ are each hydrogen or substituted or unsubstituted linear or branched C ₁ to C ₅ alkyl group, substituted or unsubstituted C ₃ to C ₈ cycloalkyl group, or substituted or unsubstituted C ₅ to The aromatic group of C ₁₂ is represented, and x and y are integers of 0-5.

Wherein R ₈ to R ₁₁ each represent hydrogen or an unsubstituted or substituted straight or branched alkyl group of C ₁ to C ₅ , and p is an integer of 5 to 500.

Wherein n is an integer from 1 to 100.

The molecular weight of the silicone crosslinking agent of Formula 1 is 300 to 30000. The crosslinking agent of Chemical Formula 1 contains a sufficient amount of silicon (Si) and serves to maintain a very small etching selectivity compared to an amorphous carbon layer, which is a lower layer during etching, for example, [2- (3,4-epoxycyclohexyl ) Ethyl] -heptaisobutyl substituted-Polyhedral Silsesquioxane (PSS) (PSS- [2- (3,4-Epoxycyclohexyl) ethyl] -Heptaisobutyl substituted).

Silicone in the composition may be included in an amount of 10 to 50% by weight based on the remaining components, except for the solvent, it is preferably included in an amount of 15 to 40% by weight.

When the silicon content is 15% by weight or more, the selectivity of the lower layer amorphous carbon when etched with O ₂ gas is 50 times or less.

The molecular weight of the novolak resin of the formula (2) is 500 ~ 50000. Since the compound of Formula 2 exhibits high absorbance, especially for an ArF light source of 193 nm, the light absorption in the wavelength region may be increased by removing reflected light and standing waves in the lower layer. Reacts with the crosslinking agents to form a crosslinked structure in the organic antireflection layer. When the molecular weight of the compound is less than 500, crosslinking cannot be sufficiently formed in the organic antireflection layer, such that the organic antireflection layer is dissolved in the photoresist solvent. The problem arises that the ratio is too small. Preferred examples of the compound of Formula 2 are those wherein R ₈ to R ₁₁ are all hydrogen, and the average molecular weight is 2000.

 The compound of Formula 3, which is optionally included in the composition of the present invention, is a compound for inducing and strengthening the crosslinking between the epoxy group of the crosslinking agent of Formula 1 and the acidic OH group of the novolak resin of Formula 2. It does not mix with photoresist. In addition, since the compound of Formula 3 includes many benzene rings, it helps to increase light absorption in the 193 nm wavelength region. More specifically, the compound of Formula 3 may use, for example, poly [(o-cresyl glycidyl ether) -co-formaldehyde].

As the thermal acid generator used in the composition for a hard mask of the present invention, a material that is conventionally used as a thermal acid generator may be generally used. Specifically, at least one selected from the group consisting of the following Chemical Formulas 4 and 5 is preferably used. Do. In the embodiment of the present invention, 2-hydroxyhexyl paratoluenylsulfonate was used as the thermal acid generator.

Wherein A is a sulfonate group,

또는

이고, Preferably

or

ego,

n is 0 or 1;

This thermal acid generator serves as a catalyst for activating the crosslinking reaction that occurs between the crosslinker and the OH group of the light absorber. After applying the composition for a hard mask of the present invention containing the thermal acid generator on a wafer and performing a thermal process such as baking, acid is generated from the thermal acid generator, and the crosslinking reaction as described above in the presence of the acid generated in this way. This happens to form a hard mask layer that does not dissolve in the solvent of the photoresist.

In addition, a photoacid generator may be introduced to the composition of the present invention to control the shape of the photoresist pattern, and any photoacid generator may be used as a compound capable of generating an acid by light. The materials used can generally be used. As the photoacid generator, sulfide-based or onium salt-based compounds are mainly used, and specific examples thereof include phthalimidotrifluoromethanesulfonate, dinitrobenzyltosylate, n-decyldisulfone, and naphthylimidotrifluoromethanesulfonate. , Diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxyphenyl sulfonium triplate, diphenyl paratoluenyl sulfonium triplate At least one from the group consisting of diphenylparaisobutylphenyl sulfonium triflate, triphenyl hexafluoro arsenate, triphenyl hexafluoro antimonate, triphenylsulfonium triflate or dibutylnaphthylsulfonium triflate It is preferable to use the selected one.

The hard mask composition of the present invention may be prepared by dissolving a crosslinking agent of Formula 1, a novolak resin of Formula 2, a thermal acid generator, optionally a compound of Formula 3, and optionally a photoacid generator in a solvent at an appropriate ratio. As a solvent used in the composition for a hard mask of the present invention, any conventional organic solvent conventionally used as a solvent for the antireflective layer composition may be used, for example, methyl 3-methoxypropionate, ethyl 3- Methoxy propionate, propylene glycol methyl ether acetate (PGMEA), cyclohexanone, 2-heptanone or ethyl lactate, and preferably methyl 3-methoxypropionate, ethyl 3-ethoxypropio Nate, cyclohexanone, and propylene glycol methyl ether acetate are mentioned, Especially preferably, propylene glycol methyl ether acetate is mentioned.

In the composition for a hard mask of the present invention, the silicone compound of Formula 1 is contained in an amount of 30 to 70 parts by weight based on 100 parts by weight of the composition, the novolak resin of the formula (2) used as a light absorber is contained in the composition It is preferably included in an amount of 20 to 200 parts by weight based on 100 parts by weight of the compound of Formula 1, and the compound of Formula 3 is preferably included in an amount of 1 to 100 parts by weight based on 100 parts by weight of the compound of Formula 1, and The generator is preferably included in an amount of 1 to 20 parts by weight based on 100 parts by weight of the compound of Formula 1, and the photoacid generator is included in an amount of 0.1 to 10 parts by weight, based on 100 parts by weight of the compound of Formula 1. It is preferably included in an amount of 1000 to 10000 parts by weight based on the total weight (100 parts by weight) of the crosslinking agent and the light absorbing agent included in the composition.

The composition of the present invention includes each component in the above composition ratio, thereby effectively preventing diffuse reflection in the photoresist underlayer, and increasing the etching selectivity between the photoresist and the hard mask, and thus, after pattern formation, By the etching conditions of the anti-reflection layer can be easily removed.

That is, the composition for a hard mask of the present invention can effectively remove diffuse reflection and standing waves in the lower layer by the novolak resin, and at the same time add a compound of Formula 3 to increase the crosslinking density even if the content of the crosslinking agent is small. The silicone component is included in the crosslinking agent to improve the etching selectivity.

The present invention also provides a method for forming an amorphous carbon layer 3 on top of an etched layer 4;

Forming a hard mask layer 12 by applying a composition for a hard mask according to the present invention on the amorphous carbon layer 3 and then performing a baking process;

Forming a photoresist pattern 5 by applying a photoresist composition on the hard mask layer 12 and performing a lithography process;

Etching the hard mask layer 12 using the photoresist pattern 5 as an etching mask to form a hard mask pattern;

Etching the amorphous carbon layer by using the hard mask pattern as an etching mask to form an amorphous carbon layer pattern; And

And forming an etched layer pattern by etching the etched layer 4 using the amorphous carbon layer pattern as an etch mask.

In the above process, the SiON hard mask layer 2 and the organic antireflective layer 1 formed on the amorphous carbon layer 3 shown in FIG. 1 are sequentially formed, as shown in FIG. 2. ) Is replaced by forming the hard mask layer 12 of the present invention. That is, in the above process, the composition for a hard mask of the present invention forms a two-layer replacement hard mask layer.

The present invention also comprises the step of forming a hard mask layer 12 by applying a composition for a hard mask according to the invention on top of the etched layer (4) and then performing a baking process;

Forming a photoresist pattern 5 by applying a photoresist composition on the hard mask layer 12 and performing a lithography process;

Etching the hard mask layer 12 using the photoresist pattern 5 as an etching mask to form a hard mask pattern;

And etching the etched layer 4 using the hard mask pattern as an etch mask to form an etched layer pattern.

In the above process, the amorphous carbon layer 3, the SiON hard mask layer 2, and the organic antireflection layer 1 are sequentially formed on the etching layer 4 shown in FIG. 1, as shown in FIG. As described above, the hard mask layer 12 of the present invention is directly formed on the etched layer 4. That is, in the above process, the composition for a hard mask of the present invention forms a three-layer replacement hard mask layer.

In the method of manufacturing a semiconductor device according to the present invention, the baking process is preferably performed for 1 to 5 minutes at a temperature of 100 ~ 300 ℃. By carrying out the bake under these conditions, an acid is generated from the thermal acid generator to form a crosslink in the hard mask layer of the present invention, thereby forming a layer that does not dissolve in the solvent of the photoresist.

In addition, in the manufacturing method according to the present invention, the baking process is performed before and after the exposure during the photoresist step of forming a photoresist pattern, the baking process is performed for 1 to 5 minutes at a temperature of 70 ~ 200 ℃ desirable.

In addition, the etching process may be performed using a CF ₄ / O ₂ mixed gas.

The antireflection layer composition and the method of manufacturing a semiconductor device according to the present invention are mainly applied to an ultrafine pattern forming process using a 193 nm ArF light source, but are performed using KrF, VUV, EUV, E-beam, X-ray or ion beam. The same can also be applied to the ultrafine pattern forming process.

The present invention also provides a semiconductor device manufactured through the pattern forming method according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.

Example 1 Preparation of Composition for Hard Mask of the Present Invention

[2- (3,4-epoxycyclohexyl) ethyl] -heptaisobutyl substituted-PSS 5g (Aldrich No. 56031-6), a crosslinking agent of formula (1), wherein the polymer of formula (2) R ₈ to R ₁₁ are all H, an average molecular weight of 2000) 5 g, a poly [(o-cresyl glycidyl ether) -co-formaldehyde] (60% solution in MEK, Aldrich No. 40551-5) 1 g, 0.85 g of 2-hydroxyhexylparatoluenylsulfonate used as a thermal acid generator and 0.05 g of triphenylsulfonium triflate as a photoacid generator were dissolved in 200 g of PGMEA as a solvent, followed by 0.2 µm fine particles. By passing through a filter to prepare a composition for a hard mask according to the present invention.

Example 2 Pattern Formation

The hard mask composition prepared in Example 1 was spin-coated at 3000 rpm on a silicon wafer, and then baked at 90 ° C. for 90 seconds to form a crosslink to form a hard mask film. The formed thickness was 950 mm 3.

On the wafer on which the hard mask film was formed, Shin-Etsu Co., Ltd. photoresist X-121 for 193 nm was coated with a thickness of 0.24 microns, baked at a temperature of 120 ° C. for 90 seconds, and then an ASF ArF scanner (NA = 0.63) was applied. It exposed using. After exposure, the plate was further baked at 120 ° C. for 90 seconds and then developed with a 2.38 wt% TMAH aqueous solution to form a final photoresist pattern as illustrated in FIG. 4.

Example 3 Etching

Using the photoresist pattern formed in Example 2 as an etching mask, the hard mask layer was etched with a CF ₄ / O ₂ mixed gas to obtain a pattern as shown in FIG. 5. However, the photo of FIG. 5 is a photo without removing the photoresist remaining after etching.

As can be seen from the above embodiment and FIGS. 4 and 5, the hard mask layer formed by the present invention has sufficient absorbance for a 193 nm light source and the like, which can effectively remove diffuse reflection from the lower layer and the like. At the same time, a resist pattern was obtained, and at the same time, an excellent etching selectivity was shown under conventional etching conditions.

Preferred embodiments of the present invention are for the purpose of illustration, and those skilled in the art will be able to make various modifications, changes, substitutions and additions through the spirit and scope of the appended claims, and such modifications may be made by the following claims. Should be seen as belonging to.

The composition of the present invention is a two-layer layer of the existing organic anti-reflection layer / SiON hard mask layer through the improved pattern uniformity and the etching selectivity in the ultrafine pattern formation and subsequent etching process of the photoresist for lithography during the semiconductor device manufacturing process or It can successfully serve as a hard mask that can replace three layers of an organic antireflection layer / SiON hard mask layer / amorphous carbon layer at one time. In addition, by using the composition for a hard mask, the manufacturing cost of the semiconductor device can be reduced and the process efficiency can be increased due to the process simplification.

Claims (16)

A composition for a hard mask comprising a compound of Formula 1, a compound of Formula 2, a thermal acid generator, and a solvent: [Formula 1]

Wherein R ₁ to R ₇ are each hydrogen or substituted or unsubstituted linear or branched C ₁ to C ₅ alkyl group, substituted or unsubstituted C ₃ to C ₈ cycloalkyl group, or substituted or unsubstituted C ₅ to An aromatic group of C ₁₂ , x and y are integers of 0 to 5, and the molecular weight of the compound is 300 to 30000; [Formula 2]

Wherein R ₈ to R ₁₁ each represent hydrogen or an unsubstituted or substituted straight or branched alkyl group of C ₁ to C ₅ , p is an integer of 5 to 500, and the molecular weight of the compound is 500 to 50000. The method of claim 1, The compound of Chemical Formula 1 is [2- (3,4-epoxycyclohexyl) ethyl] -heptaisobutyl substituted-PSS (Polyhedral Silsesquioxane), and the compound of Chemical Formula 2 is R ₈ to R ₁₁ And a compound having an average molecular weight of 2000. The method of claim 1, The compound of Formula 1 is a hard mask composition, characterized in that contained in an amount of 30 to 70 parts by weight based on 100 parts by weight of the composition. The method of claim 1, The compound of Formula 2 is included in an amount of 20 to 200 parts by weight based on 100 parts by weight of the compound of Formula 1, and the thermal acid generator is included in an amount of 1 to 20 parts by weight based on 100 parts by weight of the compound of Formula 1 Hard mask composition. The method of claim 1, A hard mask composition comprising the cross-linking agent of Formula 3 in an amount of 1 to 100 parts by weight based on 100 parts by weight of the compound of Formula 1: [Formula 3]

Wherein n is an integer from 1 to 100. The method of claim 1, A hard mask composition comprising a photoacid generator in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the compound of Formula 1. The method of claim 1, The silicon content in the composition is a hard mask composition, characterized in that 10 to 50% by weight based on the remaining components except the solvent. The method of claim 1, The solvent is at least one selected from the group consisting of methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate, cyclohexanone, 2-heptanone and ethyl lactate Hard mask composition. Forming an amorphous carbon layer on the etched layer; Forming a hard mask layer by applying a composition for a hard mask according to claim 1 on the amorphous carbon layer and then performing a baking process; Applying a photoresist composition on the hard mask layer and performing a lithography process to form a photoresist pattern; Etching the hard mask layer using the photoresist pattern as an etching mask to form a hard mask pattern; Etching the amorphous carbon layer by using the hard mask pattern as an etching mask to form an amorphous carbon layer pattern; And And etching the etched layer by using the amorphous carbon layer pattern as an etch mask to form an etched layer pattern. The method of claim 9, The baking process is performed for 1 to 5 minutes at a temperature of 100 ~ 300 ℃ manufacturing method of a semiconductor device. The method of claim 9, Wherein said lithography process uses an ArF, KrF, VUV, EUV, E-beam, X-ray or ion beam light source. The method of claim 9, The etching process is a method of manufacturing a semiconductor device, characterized in that using a CF ₄ / O ₂ mixed gas. Forming a hard mask layer by applying a composition for a hard mask according to claim 1 on the etched layer and then performing a baking process; Applying a photoresist composition on the hard mask layer and performing a lithography process to form a photoresist pattern; Etching the hard mask layer using the photoresist pattern as an etching mask to form a hard mask pattern; And And etching the etched layer using the hard mask pattern as an etch mask to form an etched layer pattern. The method of claim 13, The baking process is performed for 1 to 5 minutes at a temperature of 100 ~ 300 ℃ manufacturing method of a semiconductor device. The method of claim 13, Wherein said lithography process uses an ArF, KrF, VUV, EUV, E-beam, X-ray or ion beam light source. The method of claim 13, The etching process is a method of manufacturing a semiconductor device, characterized in that using a CF ₄ / O ₂ mixed gas.

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