KR100527288B1 - Composition for forming organic anti-reflective coating layer and method for producing semiconductor device pattern using the same - Google Patents

Abstract

In the ultrafine pattern formation process of a semiconductor device, an organic diffuse reflection prevention film forming composition and a method of forming a semiconductor device pattern using the same are provided, which are formed under the photoresist film and absorb light for exposure, thereby increasing the uniformity of the pattern. . The organic anti-reflective coating film-forming composition comprises a light absorbing agent comprising a polyvinylphenol salt represented by the following formula; A crosslinking agent capable of forming a film by a crosslinking reaction; A catalyst for promoting a crosslinking reaction of the crosslinking agent; And solvents.

In the above formula, a and b are polymerization degrees, a + b is an integer of 10 to 800, b is an integer of 10 to 800, and R is each independently hydrogen or a lower alkyl group having 1 to 4 carbon atoms.

Description

Composition for forming organic antireflection film and method for forming semiconductor device pattern using same {Composition for forming organic anti-reflective coating layer and method for producing semiconductor device pattern using the same}

The present invention relates to a composition for forming an organic anti-reflective coating, and more particularly, in an ultrafine pattern forming process of a semiconductor device, an organic layer formed under a photoresist film to absorb light for exposure, thereby increasing the uniformity of the pattern. A composition for forming an antireflection film and a method of forming a semiconductor device pattern using the same.

Currently, the memory capacity in the semiconductor memory field is 64M and 256M DRAM, and the development and mass production of 512M DRAM is progressing recently. As the high integration of the memory proceeds, the resist line width and the line width stabilization in the photolithography process are the most important factors in forming the semiconductor microcircuits. In particular, the exposure process is an important process that forms the basis for forming a semiconductor microcircuit, and is a process that greatly affects securing high resolution and improving the uniformity of the photoresist pattern. In the exposure step, it is preferable to use light having a short wavelength in order to increase the resolution. Recently, short wavelength light having a wavelength of 193 nm (ArF) is used, and when the ArF light is used, the limit resolution, that is, the limit resolution line width of the photoresist is about 0.12 to 0.08 μm although it varies slightly depending on the exposure equipment. However, if the wavelength of the exposure light is simply shortened to improve the resolution of the pattern, the optical interference effect is increased in the exposure process, and the pattern profile is deteriorated or the size uniformity is deteriorated due to notching, standing wave, or the like. There is a problem.

Therefore, in order to suppress the occurrence of notching, standing waves, etc. due to the exposure light reflected from the etched layer of the semiconductor substrate, a method of forming an anti-reflective film for absorbing light for exposure between the etched layer and the photoresist film is commonly used. . Such antireflective coatings are classified into inorganic and organic antireflective coatings according to the type of material used, and are also classified into absorption systems and interferometric antireflective coatings according to diffuse reflection mechanisms. Among the inorganic diffuse reflection prevention films, the absorption diffuse reflection prevention film is formed of TiN or amorphous carbon, and the interferometric diffuse reflection prevention film is mainly formed of SiON. Such inorganic anti-reflective coatings are mainly used for the micro pattern formation process using I-line of 365 nm wavelength, and recently, to apply inorganic anti-reflective coating using SiON to the ultra-fine pattern formation process using ArF light. Attempts are being made. However, such an inorganic antireflection film has a light reflectance of 10% or more, which is significantly lower than the organic antireflective film having a reflectivity of 1% or less, and can sufficiently suppress the interference phenomenon of 193 nm (ArF) light. Inorganic materials that can be used are not yet developed.

Therefore, in recent years, active research on organic diffuse reflection prevention film suitable for the ultrafine pattern formation process using ArF light has been actively conducted, but when the conventional organic diffuse reflection prevention film is applied to the fine pattern formation process of 0.1㎛ or less, the pattern collapses This is an impossible problem. That is, a good organic anti-reflective coating which can be used for forming a fine pattern of a semiconductor device can not only prevent the collapse of the pattern in the ultrafine pattern formation process, but also have the following basic conditions. First, there should be no phenomenon that the anti-reflective coating is dissolved and peeled off by the photoresist solvent when the process is applied. To this end, the antireflection film must have a crosslinked structure, and when forming the crosslinked structure, other impurities must not be generated by side reactions. Second, there should be no entry of chemicals such as acids and amines from the anti-reflective coating. This is because when the acid migrates from the diffuse reflection prevention film, undercutting occurs in the lower portion of the photoresist pattern, and when bases such as amines migrate, footing may occur. Third, the anti-reflective film should have a relatively fast etching rate compared to the upper photoresist film, it is possible to perform a smooth etching process using the photoresist film as a mask during etching. Fourth, in order to improve the anti-reflection efficiency, it is necessary to be able to form the diffuse reflection prevention film as thin as possible.

Accordingly, an object of the present invention is to prevent reflection of light in the process of forming a fine pattern of a semiconductor device, particularly an ultrafine pattern exposure process using ArF light (wavelength: 193 nm), thereby generating standing waves, affecting back diffraction and reflected light from a lower layer. It is to provide a composition for forming an organic diffuse reflection prevention film that can be removed or reduced.

It is another object of the present invention to provide a composition for forming an organic anti-reflective coating which is not only high in absorbance to light of a specific wavelength but also excellent in adhesion to a resist and can suppress the collapse of a pattern.

Still another object of the present invention is to provide a composition for forming an organic anti-reflective coating film which can not only form a pattern having a vertical structure but also improve the uniformity of the formed pattern, and a method of forming a semiconductor device pattern using the same.

In order to achieve the above object, the present invention is a light absorbing agent comprising a polyvinylphenol salt, preferably a polyvinylphenol salt represented by the following formula; A crosslinking agent capable of forming a film by a crosslinking reaction; A catalyst for promoting a crosslinking reaction of the crosslinking agent; And it provides a composition for forming an organic anti-reflective film comprising a solvent.

In the above formula, a and b are polymerization degrees, a + b is an integer of 10 to 800, b is an integer of 10 to 800, and R is each independently hydrogen or a lower alkyl group having 1 to 4 carbon atoms.

The present invention also comprises the steps of (a) applying the composition for forming an organic anti-reflective coating on the top of the etching layer; (b) thermosetting the composition for forming an organic anti-reflection coating applied on the etched layer to form an organic anti-reflection coating; (c) applying a photoresist on the formed organic anti-reflective coating, exposing the photoresist in a predetermined pattern, and then developing the photoresist pattern to form a photoresist pattern; And (d) etching the organic diffuse reflection prevention layer and the etched layer using the formed photoresist pattern as an etch mask to form an etched layer pattern, and a semiconductor device manufactured by the method. to provide.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The composition for forming an organic anti-reflective coating according to the present invention is a light absorbing agent comprising a polyvinylphenol salt, preferably a polyvinylphenol salt represented by the following Chemical Formula 1, a crosslinking agent capable of forming a film by a crosslinking reaction, and crosslinking of the crosslinking agent. A catalyst for promoting the reaction, and a solvent.

In Formula 1, a and b are the degree of polymerization, a + b is an integer of 10 to 800, preferably an integer of 30 to 400, b is an integer of 10 to 800, preferably an integer of 10 to 400, more Preferably it is an integer of 10-100, R is respectively independently hydrogen or a lower alkyl group of 1-4 carbon atoms, Preferably it is an ethyl group.

In the composition for forming an organic anti-reflective coating according to the present invention, the degree of polymerization of the polyvinylphenol salt used as the light absorbing agent may vary depending on the thickness, reflectance, light source used, manufactured device, etc. of the anti-reflective coating to be formed, but is preferably It is 10-800, More preferably, it is 30-400, The number of bases contained in the said polyvinyl phenol salt is an integer of 10-800, Preferably it is 10-400, More preferably, it is an integer of 10-100. More specifically, the phenol salt contained in the polyvinyl phenol salt of Chemical Formula 1 is preferably 1 to 20% in molar ratio with respect to the entire phenol group and phenol salt included in the polyvinyl phenol salt, and is 2 to 10%. More preferred. If the degree of polymerization of the polyvinylphenol salt is too high or low, the handleability is lowered, and when the number of bases included in the polyvinylphenol salt is less than 10, there is a disadvantage that the light reflectivity is increased. The polyvinylphenyl salt is synthesized by dissolving polyvinylphenol having a desired degree of polymerization in an organic solvent such as acetone, and then adding an appropriate amount of an amine compound and reacting for about 10 to 60 hours, preferably 40 to 60, It can manufacture by adding an amine compound at the time of superposition | polymerization of polyvinyl phenol. Moreover, the other crosslinkable monomer may be copolymerized with the said polyvinyl phenol salt as needed.

In the composition for forming an organic anti-reflective coating according to the present invention, the content of the light absorbing agent of Chemical Formula 1 may vary depending on the reflectance of the desired light, but is preferably 5 to 400 parts by weight based on 100 parts by weight of the crosslinking agent. For example, if the light reflectance is to be adjusted to 5% or more, the content of the light absorber should be 15% by weight or less with respect to the entire crosslinking agent and the light absorber, and the light absorber may be adjusted to 1% or less. The content is about 30% by weight or more. When the content of the light absorbing agent is less than 5 parts by weight based on 100 parts by weight of the crosslinking agent, the light reflectivity is too large, so that the antireflection effect is insignificant. When the content of the light absorber exceeds 400 parts by weight, the etching resistance of the antireflection film is excessively increased, and the etching rate is higher than that of the photosensitive agent. There is a fear that the basic properties of the antireflection film, which should be large, may not be satisfied.

As the crosslinking agent used in the composition for forming an organic anti-reflective coating of the present invention, various heat or photocrosslinkable polymers which are commonly used can be used in a wide range. For example, as the crosslinking agent, polyvinyl alcohol (PVA), sodium dichromate (SDC), ammonium dichromate (ADC), 4,4'-diazidobenzalacetophenone-2-sulfonate, 4,4'-dia Zidostilbene-2,2'-disulfonate, 4,4'- diazidostilbene-gamma-carboxylic acid, etc. can be used, It is preferable to use the polymer containing an acetal group, The polymer of following General formula (2) It is more preferable to use a crosslinking agent.

In Formula 2, R ₁ to R ₅ are each independently hydrogen or a linear or branched substituted alkyl group having 1 to 5 carbon atoms, preferably R ₁ and R ₂ are each independently an alkyl group having 1 to 4 carbon atoms, R ₃ is hydrogen or a methyl group, R ₄ and R ₅ are hydrogen, and a is an integer from 10 to 100.

The catalyst included in the composition for forming an organic anti-reflective coating according to the present invention causes a crosslinking mechanism of the crosslinking agent to act as a crosslinking initiator for curing the organic anti-reflective coating, and the crosslinking agent and, if necessary, the light absorbing agent. Various catalysts for promoting the crosslinking reaction of the crosslinking components included can be used in the present invention. As such a catalyst, a conventional thermal acid generator may be used, and 2-hydroxycyclohexyl paratoluenesulfonate represented by the following Chemical Formula 3 may be used (2-hydroxycyclohexyl p-toluenesulfonate). In the composition for forming an organic anti-reflective coating film of the present invention, the content of the thermal acid generator is preferably 5 to 200 parts by weight based on 100 parts by weight of the crosslinking agent. If the content of the thermal acid generator is less than 5 parts by weight, the crosslinking agent may not be sufficiently crosslinked, and there is no additional advantage even if it exceeds 200 parts by weight.

In addition, the organic anti-reflective coating composition of the present invention includes an organic solvent for dissolving a crosslinking agent, a thermal acid generator, a light absorbing agent and the like. As such an organic solvent, various organic solvents generally used in the composition for forming an organic anti-reflective coating film can be widely used. For example, cyclohexane, propylene glycol methyl ether acetate (PGMEA), ethyl lactate, or the like can be used alone or mixed. It can be used as the organic solvent, it is more preferable to use cyclohexane. The content of the organic solvent is not particularly limited as long as it can sufficiently dissolve a crosslinking agent, a thermal acid generator, a light absorbing agent, and the like, preferably 500 to 10,000 parts by weight based on 100 parts by weight of the crosslinking agent. If the amount of the organic solvent used is less than 500 parts by weight, the thickness of the antireflection film is too thick, so that the photoresist may be excessively etched when the antireflection film is etched later. It is difficult to obtain a protective film of a desired thickness.

After applying such an organic anti-reflective coating film-forming composition to a layer to be etched, such as a wafer, when heat treatment is performed, an acid is generated from the thermal acid generator, and the crosslinking agent is activated by the generated acid and crosslinks with the light absorber, thereby dissolving it in a photosensitive agent. A crosslinked organic diffuse reflection prevention film is formed.

Next, a method for forming a semiconductor element pattern using the composition for forming an organic anti-reflection coating according to the present invention will be described. In the present invention, the "semiconductor element pattern" includes not only a semiconductor element such as a memory but also a circuit pattern of various display elements such as a liquid crystal display device and an organic light emitting display device, and also includes a physical structure such as an insulating film used for the elements. It includes an element of.

In order to form the semiconductor device pattern according to the present invention, first, the composition for forming the organic anti-reflective coating film according to the present invention on the etching target layer, such as a silicon wafer or an aluminum substrate, is usually coated with a spin coating method, a dip coating method, a roll coating method, and the like. After coating in the step (step a), the organic anti-reflective coating composition is cross-linked to perform a heat curing process to form an organic anti-reflective coating (step b). By such a thermosetting process, the residual solvent in the organic anti-reflective coating composition is removed, an acid is generated from the thermal acid generator, and the light absorbing agent and the crosslinking agent are crosslinked, thereby forming an organic anti-reflective coating which is not dissolved in the photosensitizer. Therefore, the temperature and time of the thermal curing process is appropriately selected so that the thermal acid generator can be decomposed, and the residual solvent removal and the crosslinking of the organic anti-reflective coating composition can proceed sufficiently. Typically, the thermosetting process may be performed for 1 to 5 minutes at a temperature of 150 to 300 ℃, when the heat curing temperature and time is less than the above range does not occur sufficient heat curing, even if the above range is an additional advantage none.

After applying the photoresist composition (photosensitive agent) on the organic anti-reflective film formed as described above, it is exposed and developed to form a predetermined pattern (step c). In this case, a process of thermosetting the photoresist layer may be further performed before and / or after the exposure process, and the thermosetting process may be performed at 70 to 250 ° C., which is a heat treatment condition of a conventional photoresist layer. . At this time, if the thermosetting temperature is less than 70 ℃, the photoresist layer is not sufficiently thermally cured, even if it exceeds 250 ℃ it is no longer helpful for thermal curing. As the light source of the exposure process, deep ultra violet (DUV), E-beam, including F ₂ laser (157 nm), ArF (193 nm), KrF (248 nm), EUV (extremely ultraviolet), etc. X-rays, ion beams and the like can be used. After exposing the photoresist film in a predetermined pattern in this manner, by removing the exposed or unexposed photoresist region using a developer, a photoresist pattern having a uniform fine pattern of vertical structure can be formed. As the developer, an alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, tetramethyl ammonium hydroxide (TMAH), etc. is preferably used. Can also be used. Moreover, after developing using alkaline aqueous solution, it is preferable to wash a wafer with ultrapure water. Next, the semiconductor device pattern may be formed by etching the diffuse reflection prevention layer and the etched layer under the photoresist using the photoresist pattern thus formed as an etch mask to form an etched layer pattern (step d).

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are merely to illustrate the invention, the present invention is not limited to the following examples.

Preparation Example Synthesis of Light Absorber

After dissolving 300 g of polyvinyl phenol (molecular weight 8,000) completely in 800 g of acetone, 9 g of triethylamine was added and reacted at room temperature for about 48 hours. A salt was obtained. H-NMR (solvent CDCl ₃ ) was measured with respect to the obtained polyvinylphenol salt, and the results are shown in FIG. 1. For comparison, H-NMR (solvent is acetone d ₆ ) with respect to polyvinylphenol, which is a conventional light absorber, was compared. Was measured and the result is shown in FIG. Comparing the NMR spectra of FIGS. 1 and 2, it can be seen that the phenol peak appearing at 7.7 ppm of FIG. 2 hardly appears in FIG. 1. Indeed, 252 g of triethylamine are required to convert all the phenolic groups of 300 g of polyvinylphenol to salts, but the cause is not known. However, even when only about 9 g of triethylamine is used, the -OH peak of phenol on NMR is hardly obtained. Did not appear.

Example 1 Preparation of Organic Anti-Reflection Prevention Film Formation

0.4 g of the light absorbing agent according to the preparation example, the crosslinking agent of Formula 2 (R ₁ and R ₂ is methyl, R ₃ to R ₅ is hydrogen, the degree of polymerization a is 56) 0.6 g, 2-hydroxy as a thermal acid generator 0.05 g of cyclohexyl paratoluenesulfonate was dissolved in 40 g of propylene glycol methyl ether acetate (PGMEA) solvent, and then filtered through a 0.2 μm fine filter to prepare an organic anti-reflective coating film-forming composition.

[Comparative Example 1] Preparation of Organic Anti-Reflection Prevention Film Formation

An organic anti-reflective coating film-forming composition was prepared in the same manner as in Example 1, except that 0.4 g of polyvinylphenol was used as the light absorbing agent.

[Comparative Example 2] Preparation of Organic Anti-Reflection Prevention Film Formation

An organic anti-reflective coating film-forming composition was prepared in the same manner as in Comparative Example 2 except that 0.3 g of triethylamine was further included.

Example 2 Formation of Photoresist Pattern

The composition for forming an organic anti-reflective coating film according to Example 1 was spin-coated to a thickness of about 350 GPa on a silicon wafer, and crosslinked by thermal curing at 205 ° C. for 90 seconds. An ArF photosensitive agent (manufacturer: Dongjin Semichem Co., Ltd.) was coated on the crosslinked organic antireflective coating, thermally cured at 100 ° C. for 90 seconds, and then exposed in a predetermined pattern using an ArF exposure apparatus (manufactured by ASML). Thermal curing was again at 90 ° C. for 90 seconds. Next, the wafer was developed using a 2.38 wt% developer of tetramethylammonium hydroxide (TMAH) to obtain a photoresist pattern, and the results are shown in FIGS. 3 (line width 100 nm) and 4 (line width 70 nm). . 3 and 4, it can be seen that when the composition for forming an organic anti-reflective coating film obtained in Example 1 is used, the profile of the pattern is formed in a very uniform vertical form, and the adhesion between the wafer and the photoresist pattern is excellent. As shown in FIG. 4, it can be seen that a fine pattern having a line width of about 70 nm does not fall and forms a stable vertical structure.

Comparative Example 3 Formation of Photoresist Pattern

A photoresist pattern was obtained in the same manner as in Example 2, except that the composition according to Comparative Example 1 was used instead of the composition for forming an organic anti-reflective coating according to Example 1, and the results are shown in FIGS. 5 (120 nm in width) and 6. (Line width 100 nm) is shown. Referring to FIG. 5, when the composition for forming an organic anti-reflective coating film obtained in Comparative Example 1 is used, it can be seen that the profile of the pattern is formed in an inverted trapezoidal shape. As shown in FIG. 6, the adhesion between the wafer and the photoresist pattern is shown. It is not good and it can be seen that the pattern collapses even when a pattern having a line width of about 100 nm is formed.

Comparative Example 4 Formation of Photoresist Pattern

A photoresist pattern was obtained in the same manner as in Example 2, except that the composition according to Comparative Example 2 was used instead of the composition for forming an organic anti-reflective coating according to Example 1, and the results are shown in FIG. 7 (line width 100 nm). It was. From Fig. 7, using the composition for forming an organic anti-reflective coating film according to Comparative Example 2, the profile of the pattern is formed in a substantially vertical form, but if you look closely at the square region of Figure 7 (a side is inclined and the other is vertical) It can be seen that the pattern is inclined to both sides or left and right, it is difficult to use such a pattern in the actual semiconductor manufacturing. This is because triethylamine molecules are not uniformly distributed when triethylamine is directly injected into the composition and patterned. Therefore, it can be seen that it is much more effective to prepare in the form of polyvinylphenol salt than to add triethylamine directly to the composition.

From the above examples and comparative examples, compared with the conventional organic antireflection coating composition, the organic antireflection coating composition according to the present invention containing a polyvinyl phenol salt not only forms a photoresist pattern vertically, but also a photoresist pattern and a wafer. It can be seen that it is possible to prevent the collapse of the pattern by improving the adhesion of the.

As described above, when the antireflection film is formed using the composition according to the present invention, standing wave effects, diffuse reflection generation, and line width (CD) are caused by optical properties of the etched layer or variations in thickness of the resist film. Not only can the fluctuation be significantly reduced, but also the adhesion between the organic diffuse reflection prevention film and the resist film can be improved, thereby reducing the pattern collapse of the resist pattern by the negative slope. Therefore, the composition for forming an organic anti-reflective coating according to the present invention can form a stable ultrafine pattern in the production of 64M, 256M, 512M, 1G, 4G, 16G DRAM semiconductor, it is possible to increase the yield of the product.

1 and 2 are NMR spectra of polyvinylphenol salts, which are light absorbers used in the present invention, and polyvinylphenol, which is a conventional light absorber, respectively.

3 and 4 are electron micrographs of the photoresist pattern (line width 100nm and 70nm, respectively) formed using the composition for forming an organic anti-reflective film according to an embodiment of the present invention.

5 and 6 are electron micrographs of the photoresist patterns (line width 120nm and 100nm, respectively) formed using the composition for forming an organic anti-reflective film according to Comparative Example 1.

7 is an electron micrograph of a photoresist pattern (line width 100 nm) formed using the composition for forming an organic anti-reflective coating film according to Comparative Example 2. FIG.

Claims (11)

Light absorbing agents including polyvinylphenol salts; A crosslinking agent capable of forming a film by a crosslinking reaction; A catalyst for promoting a crosslinking reaction of the crosslinking agent; And An organic diffuse reflection prevention film forming composition comprising a solvent. The composition of claim 1, wherein the polyvinylphenol salt is represented by the following Chemical Formula 1. [Formula 1] In Formula 1, a and b are degrees of polymerization, a + b is an integer of 10 to 800, b is an integer of 10 to 800, and each R is independently hydrogen or a lower alkyl group having 1 to 4 carbon atoms. The amount of the light absorbing agent is 5 to 400 parts by weight, the amount of the catalyst is 5 to 200 parts by weight, and the amount of the solvent is 500 to 10,000 parts by weight based on 100 parts by weight of the crosslinking agent. The composition for phosphorus organic diffuse reflection prevention film formation. The composition of claim 2, wherein b is an integer of 10 to 400 and R is an ethyl group. The composition of claim 1, wherein the crosslinking agent is a polymer represented by the following Chemical Formula 2. [Formula 2] In Formula 2, R ₁ to R ₅ are each independently hydrogen or a linear or branched substituted alkyl group having 1 to 5 carbon atoms, and a is an integer of 10 to 100. The composition for forming an organic anti-reflection coating according to claim 1, wherein the catalyst is 2-hydroxycyclohexyl paratoluenesulfonate. The composition of claim 1, wherein the solvent is selected from the group consisting of cyclohexane, propylene glycol methyl ether acetate, ethyl lactate, and mixtures thereof. (a) applying the composition for forming an organic anti-reflection coating according to claim 1 on the upper portion of the etching layer; (b) thermosetting the composition for forming an organic anti-reflection coating applied on the etched layer to form an organic anti-reflection coating; (c) applying a photoresist on the formed organic anti-reflective coating, exposing the photoresist in a predetermined pattern, and then developing the photoresist pattern to form a photoresist pattern; And (d) etching the organic diffuse reflection prevention layer and the etched layer using the formed photoresist pattern as an etch mask to form an etched layer pattern. The method of claim 8, wherein the step of thermosetting the composition for forming an organic anti-reflective coating film is performed by heating at 150 to 300 ° C. for 1 to 5 minutes. The method of claim 8, wherein the exposure process is performed by light selected from the group consisting of F ₂ laser, ArF, KrF, far ultraviolet rays, E-beam, X-ray, and ion beam. . A semiconductor device manufactured by the method according to any one of claims 8 to 10.