KR20050087419A - Photosensitive polymer and chemically amplified photoresist composition including the same - Google Patents

Abstract

By having a low activation energy, a photosensitive polymer resin and a chemically amplified photoresist composition including the same are disclosed which can reduce the line width change in a post-exposure heating process. The photosensitive polymer resin is represented by the following formula.

In the above formula, R is a methyl or ethyl group, R ^* is hydrogen or a methyl group, R ₁ and R ₂ are each independently hydrogen, methyl or CF ₃ , and R ₃ is an alkyl, cycloalkyl group, or ether group or ester group It is a cycloalkyl group containing, R <_4> is hydroxyalkyl, the hydroxyalkyl which has a halogen substituent, or the cycloalkyl group containing an ether group or an ester group. In addition, the a, b, c and d is the number of each repeating unit, the molar ratio of a: b: c: d is 1 to 40: 1 to 40: 1 to 50: 1 to 50.

Description

Photosensitive polymer resin and chemically amplified photoresist composition including the same {Photosensitive polymer and chemically amplified photoresist composition including the same}

The present invention relates to a photosensitive polymer resin and a chemically amplified photoresist composition comprising the same, and more particularly, having a low activation energy, thereby reducing line width variation in a post exposure bake (PEB) process. It relates to a photosensitive polymer resin and a chemically amplified photoresist composition comprising the same.

Recently, with the high integration of semiconductor integrated circuit devices, the development of dynamic random access memory (hereinafter, referred to as "DRAM") having a storage capacity of more than a gigabit level has been actively developed. In order to manufacture DRAMs of 1 gigabit or more, an extremely fine pattern having a line width of 100 nm or less should be formed.For this purpose, KrF excimer laser (248 nm) using shorter wavelengths of light than g-line (436 nm) and i-line (365 nm) is used. Photolithography technology using ArF excimer laser (193nm) as an exposure source has been introduced, while it has high resolution at short wavelength (248nm or less than 193nm), as well as transparency and dry etching resistance. At the same time, development of a photoresist composition excellent in adhesion to a lower film quality and developability in an aqueous 2.38 wt% tetramethylammonium hydroxide (TMAH) solution widely used as a developer is being progressed. In particular, as the pattern becomes finer, the photo and etching process margins must be reduced. Therefore, the importance of improving the transparency of the resist composition, reducing the line edge roughness, and decreasing the line width change due to the post-exposure heating (PEB) temperature is important. It is increasing.

In general, a positive chemically amplified photoresist is composed of a photoacid generator (PAG) which generates an acid component by exposure and a photosensitive polymer resin having a protecting group decomposed by an acid catalyst. When the chemically amplified photoresist is exposed, an acid component is generated from the photoacid generator, and the generated acid component decomposes in a chain a protecting group bonded to the skeleton of the polymer resin, thereby changing the solubility of the polymer resin, thereby developing the process. After that, a pattern having a high contrast is formed. Such chemically amplified photoresist performs a post-exposure heating (PEB) process in order to activate and diffuse an acid component present in the exposed photoresist composition, wherein the heated acid component is a photoresist of the non-exposed part. By penetrating into the furnace, the solubility of the non-exposed portion is increased, thereby changing the line width of the photoresist pattern, causing the pattern to collapse, and line edge roughness.

Accordingly, an object of the present invention is to reduce the line width change, line edge roughness, etc. by the post-exposure heating (PEB) process, to form a fine pattern stably, a chemically amplified photoresist composition comprising the same To provide.

Another object of the present invention is to provide a photosensitive polymer resin and a chemically amplified photoresist composition including the same, by performing a post-exposure heating (PEB) process at a low temperature, so that the solubility change of the non-exposed part can be suppressed.

Still another object of the present invention is to provide a method of forming a photoresist pattern using the chemically amplified photoresist composition.

In order to achieve the above object, the present invention provides a photosensitive polymer resin represented by the following formula (1).

[Formula 1]

In Formula 1, R is a methyl or ethyl group, R ^* is hydrogen or a methyl group, R ₁ and R ₂ are each independently hydrogen, methyl or CF ₃ , R ₃ is alkyl having 1 to 20 carbons, 3 to C A cycloalkyl group having 40 cycloalkyls or a cycloalkyl group having 5 to 10 carbon atoms including an ether group or an ester group, R ₄ is a hydroxyalkyl having 1 to 20 carbon atoms, a hydroxyalkyl having 1 to 20 carbon atoms, or an ether group having a halogen substituent Or a cycloalkyl group having 5 to 10 carbon atoms including an ester group. In addition, a, b, c and d is the number of each repeating unit constituting the photosensitive polymer resin, the mole ratio of a: b: c: d is 1 to 40: 1 to 40: 1 to 50: 1 to 50.

The present invention also provides a chemically amplified photoresist composition comprising a photosensitive polymer resin, a photoacid generator and an organic solvent represented by Formula 1 and a method of forming a photoresist pattern using the chemically amplified photoresist composition.

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

The photosensitive polymer resin according to the present invention is used to prepare a chemically amplified photoresist composition, and is represented by the following Chemical Formula 1.

In Formula 1, R is a methyl or ethyl group, R ^* is hydrogen or a methyl group, R ₁ and R ₂ are each independently hydrogen, methyl or CF ₃ , R ₃ is an acid-sensitive protecting group, 1 to 20 carbon atoms Is an alkyl, a cycloalkyl group having 3 to 40 carbon atoms, preferably 5 to 30 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms including an ether group or an ester group, R ₄ is a hydroxyalkyl having 1 to 20 carbon atoms, a halogen substituent Hydroxyalkyl having 1 to 20 carbon atoms or a cycloalkyl group having 5 to 10 carbon atoms including an ether group or an ester group. In addition, a, b, c and d is the number of each repeating unit constituting the photosensitive polymer resin, the mole ratio of a: b: c: d is 1 to 40: 1 to 40: 1 to 50: 1 to 50.

A more preferred example of the photosensitive polymer resin according to the present invention is to have a structure of the formula 1a to 1g.

In Formulas 1a to 1g, a, b, c, and d are as defined in Formula 1.

Since the photosensitive polymer resin includes bulky aliphatic cyclized hydrocarbons, it improves the dry etching resistance of the photoresist and, unlike the conventional deprotection group, has a low activation energy. In addition, in Chemical Formula 1, R may be both methyl or ethyl, but more preferably, ethyl. In the process of deprotection by acid, an ethyl group having a large electron donation is more easily than a methyl group. It is deprotected. Since the photosensitive polymer resin has a low activation energy and is easily deprotected by an acid, post-exposure heating (PEB) can be performed at a relatively low temperature, thereby reducing diffusion of an acid component into the non-exposed part. The line width change by the post-exposure heating (PEB) process can be reduced.

The photosensitive polymer resin according to the present invention polymerizes an ethylene-containing monomer and a (meth) acrylate monomer in the presence of a suitable initiator such as azobis (isobutylonitrile) (AIBN) and an organic solvent such as tetrahydrofuran (THF). Preferably, it may be prepared by ethylene polymerization, and the weight average molecular weight of the polymerized photosensitive polymer resin is 3,000 to 100,000, and the polydispersity is preferably 1.0 to 5.0. The polymerization reaction is preferably carried out in an inert gas atmosphere such as nitrogen, argon, preferred reaction temperature is 60 to 70 ℃, preferred reaction time is 4 to 230 hours. Here, if the weight average molecular weight, the ratio of a, b, c and d, and the polydispersity are outside the above ranges, the physical properties of the photoresist film may be lowered, the photoresist film may be difficult to form, and the contrast of the pattern may be lowered. There is. In addition, in the formula 1, each repeating unit has a meaning only in relative content with respect to other repeating units in the polymer resin, and it is apparent that the order of bonding of each repeating unit has no special meaning.

The chemically amplified photoresist composition according to the present invention comprises a) a photosensitive polymer resin represented by Chemical Formula 1, b) a photoacid generator (PAG) for generating an acid, and c) an organic solvent. Accordingly, various additives may be further included. The content of the photosensitive polymer resin of Chemical Formula 1 is preferably 1 to 30% by weight based on the total photoresist composition, and if the content of the photosensitive polymer resin is less than 1% by weight, the resist layer remaining after coating is too thin to be desired. It is difficult to form the pattern of thickness, and when it exceeds 30 weight%, there exists a possibility that coating uniformity may fall. B) The photoacid generator generates an acid component such as H + by exposure to induce a chemical amplification action, and a photoacid generator commonly known in the art may be widely used in the present invention. For example, U.S. Patent No. 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (Nov. 28, 1996), European Patent EP 0 794 458 (September 10, 1997), EP 0 789 278 (August 13, 1997), U.S. Patent No. 5,750,680 (May 12, 1998), 6,051,678 (April 18, 2000), UK Patent GB 2,345,286 (July 5, 2000), U.S. Patent No. 6,132,926 (October 17, 2000), 6,143,463 (November 7, 2000), 6,150,069 (November 21), 6,180,316 (2001) 1.30), 6,225,020 (May 1, 2001), 6,235,448 (May 22, 2001), 6,235,447 (May 22, 2001) and the like can be used. Specifically, as the photoacid generator, organic sulfonic acid and / or onium salt-based compounds may be used, and in particular, phthalimido trifluoro methane sulfonate and dinitrobenzyl tosylate having low absorbance at 157 nm and 193 nm. (dinitrobenzyltosylate), n-decyl disulfone and naphthyl imidotrifluoromethane sulfonate are preferably used alone or in combination, and together with diphenyl Urethritis hexafluorophosphate, Diphenyl iodo Salt hexafluoroarsenate, Diphenyl iodo Salt hexafluoroantimonate, Diphenyl paramethoxyphenylsulfonium triflate, Diphenyl paratoluenylsulfonium triflate, Diphenylpara Isobutylphenylsulfonium triflate, triphenylsulfonium hexafluoroarsenei , Triphenyl sulfonium hexafluoro may also be used to antimonate, triphenyl sulfonium triflate and dibutyl naphthyl tilseol sulfonium photo-acid generator selected from the group consisting of triflate claim. The content of the photoacid generator is preferably 0.1 to 20% by weight based on the total photoresist composition. If the content of the photoacid generator is less than 0.1% by weight, the sensitivity of the photoresist to light is weakened, and the amount of acid components generated by exposure is low, which may make it difficult to deprotect the protecting group, and exceeds 20% by weight. If so, the photoacid generator absorbs a lot of ultraviolet rays and excessive acid is generated, resulting in poor pattern cross section.

C) As the organic solvent constituting the remaining components of the photoresist composition according to the present invention can be used a wide variety of organic solvents commonly used in the preparation of the photoresist composition. Non-limiting examples of such organic solvents are U.S. Patent No. 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (Nov. 28, 1996). ), EP 0 794 458 (September 10, 1997), EP 0 789 278 (August 13, 1997), US Patent No. 5,750,680 (May 12, 1998), US Patent No. 6,051,678 (2000). 4.18), British Patent GB 2,345,286 (July 5, 2000), US Patent No. 6,132,926 (October 17, 2000), 6,143,463 (7/2000), 6,150,069 (11/21/2000), 6,180.316 (January 30, 2001), 6,225,020 (May 1, 2001), 6,235,448 (May 22, 2001), 6,235,447 (May 22, 2001), etc. may be used. Preferably diethyleneglycol diethylether, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate, cyclohexanone, 2-heptanone, ethyl lactate Etc. can be used alone or in combination.

In addition, the photoresist composition according to the present invention may further include an organic base as needed, non-limiting examples of the organic base is triethylamine, triisobutylamine, triisooctylamine, diethanolamine, triethanol Amines, mixtures thereof and the like can be exemplified. The amount of the organic base used is preferably 0.01 to 10.00% by weight based on the total photoresist composition. The photoresist composition according to the present invention may be prepared by mixing the photosensitive polymer resin, a photoacid generator, an organic solvent, and various additives as necessary, and filtering by a filter, wherein the solid content concentration in the total photoresist composition is 1 to It is preferable to make it 30 weight%.

In order to form a photoresist pattern using the chemically amplified photoresist composition according to the present invention, first, the photoresist composition is applied to a substrate such as a silicon wafer or an aluminum substrate using a spin coater to form a photoresist film. The conventional photolithography process may be used in which the photoresist film is exposed to a predetermined pattern, and then the exposed photoresist pattern is post-exposure heated (PEB) and developed. The exposure process is performed by an ArF, Extreme Ultra Violet (EUV), Vacuum Ultra Violet (VUV), E-beam, X-ray, ion beam, or Immersion Lithography process. Can be. In addition, as the developer used in the developing step, an alkaline aqueous solution in which alkaline compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate and tetramethylammonium hydroxide (TMAH) are dissolved at a concentration of 0.1 to 10% by weight may be used. In accordance with the present invention, an appropriate amount of a water-soluble organic solvent such as methanol or ethanol and a surfactant may be added to the developer. In addition, after the development process, the cleaning process may be further performed to clean the substrate with ultrapure water.

Hereinafter, the present invention will be described in more detail with reference to specific examples. The following examples are intended to illustrate the present invention more specifically, but the scope of the present invention is not limited by the following examples.

Example 1 Synthesis of Photosensitive Polymer Resin Represented by Chemical Formula 1a

2-ethyl-2-dicyclohexyl-5-norbornene-2-carboxylate 0.161mo1, maleic anhydride 0.161mol, 2-ethyl-2-adamantyl methacrylate 0.05mol, hydroxyadamantyl methacrylate 0.05 mol rate and 10 g of azobis (isobutyronitrile) (AIBN) were dissolved in 60 g of dry THF and the reaction was polymerized at 60 ° C. for 24 hours. After the polymerization was completed, the reactant was slowly dropped into an excess of hexane / methanol mixed solution, precipitated, dissolved in THF, and reprecipitated in a hexane / methanol mixed solution to obtain a target polymer resin in a yield of 53%. The weight average molecular weight and the polydispersity of the obtained polymer resin were 8,700 and 1.92, respectively.

Example 2 Synthesis of Photosensitive Polymer Resin Represented by Chemical Formula 1b

A polymer resin was obtained in the same manner as in Example 1, except that 0.05 mol of gamma-butylarolactone methacrylate was used instead of 0.05 mol of hydroxyadamantyl methacrylate. The weight average molecular weight and the polydispersity of the obtained polymer resin were 9,300 and 1.88, respectively, and the yield was 51%.

Example 3 Synthesis of Photosensitive Polymer Resin Represented by Chemical Formula 1c

A polymer resin was obtained in the same manner as in Example 1, except that 0.05 mol of mechatronic lactone methacrylate was used instead of 0.05 mol of hydroxyadamantyl methacrylate. The weight average molecular weight and the polydispersity of the obtained polymer resin were 9,800 and 1.90, respectively, and the yield was 53%.

Example 4 Synthesis of Photosensitive Polymer Resin Represented by Chemical Formula 1d

A polymer resin was obtained in the same manner as in Example 1 except that 0.05 mol of 2-tetrahydroxypyranyl methacrylate was used instead of 0.05 mol of 2-ethyl-2-adamantyl methacrylate. The weight average molecular weight and the polydispersity of the obtained polymer resin were 8,500 and 1.79, respectively, and the yield was 48%.

Example 5 Synthesis of Photosensitive Polymer Resin Represented by Chemical Formula 1e

0.161 mol of 2-ethyl-2-dicyclohexyl-5-norbornene-2-carboxylate, 0.161 mol of maleic anhydride, 0.05 mol of 2-tetrahydropyranyl methacrylate, and gamma-butyl as monomers A polymer resin was obtained in the same manner as in Example 1 except that 0.05 mol of lactone methacrylate was used. The weight average molecular weight and the polydispersity of the obtained polymer resin were 9,000 and 1.80, respectively, and the yield was 51%.

Example 6 Synthesis of Photosensitive Polymer Resin Represented by Chemical Formula 1f

0.161 mol of 2-ethyl-2-dicyclohexyl-5-norbornene-2-carboxylate, 0.161 mol of maleic anhydride, 0.05 mol of 2-tetrahydropyranyl methacrylate, and mevalonic lactone as monomers Polymer resin was obtained by the same method as Example 1 except for using 0.05 mol of methacrylate. The weight average molecular weight and the polydispersity of the obtained polymer resin were 8,800 and 1.89, respectively, and the yield was 50%.

Activation energy investigation of the prepared photosensitive polymer resin

The activation energy of the photosensitive polymer resins obtained in Examples 1 to 6 and the photosensitive polymer resins (copolymers) represented by the following Chemical Formulas 2 and 3 were compared. The photosensitive polymer resins represented by Chemical Formulas 2 and 3 were synthesized in the same manner as in Example 1 using the respective monomers in the same molar ratio, and the weight average molecular weights were 8,000 and 8,800, respectively, and the polydispersities were 2.0 and 2.1, respectively. .

For the activation energy irradiation, 0.1% by weight of sulfuric acid was added to the photosensitive polymer resin, and dissolved in a solvent such that the content of the photosensitive polymer resin was 12 wt% to prepare a photoresist composition. The prepared photoresist composition was uniformly coated on a silicon wafer with a thickness of 0.3 μm, and then heated with varying temperature, followed by 60 seconds using 2.38% by weight of tetramethylammonium hydroxide (TMAH) solution. It was developed, and the thickness of the photoresist film remaining after the development was examined and shown in FIG. 1.

As shown in FIG. 1, it can be seen that in the photosensitive polymer resins represented by Chemical Formulas 1a to 1f, almost no photoresist film remains after development in the entire experiment temperature including relatively low temperature. Therefore, it can be seen that the activation energy of the photosensitive polymer resins represented by Chemical Formulas 1a to 1f is low, and is easily attacked by acid, so that the functional group is deprotected. On the other hand, the photoresist film made of the photosensitive polymer resins represented by the formulas (2) and (3) does not partially develop at low temperatures, or does not show a large change in film thickness even at high temperatures. This means that the deprotecting functional group of formula (2) has a high activation energy.

Example 7 Investigation of Line Width Change According to Formation of Photoresist Pattern and Post-Exposure Heating

2.0 g of each photosensitive polymer resin and 0.02 g of triphenyl sulfonium triflate (TPS-105) obtained in Examples 1 to 6 were completely dissolved in 17 g of propylene glycol monomethyl ether acetate (PGMEA), followed by a 0.2 μm disc filter. Filtration was carried out to obtain a photoresist composition. The resulting photoresist composition was coated on a silicon wafer treated with hexamethyldisilazane (HMDS) to a thickness of about 0.30 μm. The wafer coated with the photoresist composition was prebaked at 100 ° C. for 90 seconds, exposed in a predetermined pattern using an ArF excimer laser having a numerical aperture of 0.60, and then the exposed wafer was 90 at 100 to 130 (± 5 ° C.). Post exposure heat (PEB) for seconds. The post-exposure heated (PEB) wafer was developed for 30 seconds using a 2.38 wt% tetramethylammonium hydroxide (TMAH) solution to obtain equal lines and space patterns of 0.1 μm and 0.14 μm. The photoresist pattern obtained was examined for the line width change according to the post-exposure heating (PEB) temperature, and the results are shown in Table 1 and FIG. 2.

PEB (℃) Line width change size (nm) Eop (mJ / cm ² ) PEB (℃) Line width change size (nm) Eop (mJ / cm ² ) 100 nm 140 nm 100 nm 140 nm Formula 1a 100 3.24 4.22 23 130 - - - Formula 1b 100 3.15 4.69 24 130 - - - Formula 1c 100 3.58 4.48 22 130 - - - Formula 1d 100 4.02 4.88 25 130 - - - Formula 1e 100 4.10 4.96 24 130 - - - Formula 1f 100 4.22 5.05 20 130 - - - Formula 2 100 - - - 130 5.24 6.54 28 Formula 3 100 - - - 130 6.85 7.98 26

The photoresist using the polymer resins of Formulas 1a to 1f having a small activation energy did not have a pattern at a high PEB temperature of 130 ° C., and thus the line width change could not be confirmed. This is due to the diffusion of acid to the non-exposed areas, the polymer resin of the non-exposed areas is deprotected by the acid, it is determined that not only the pattern but also the film loss. From Table 1, it can be seen that the higher the post-exposure heating (PEB) temperature, the larger the diffusion of the acid, the more severe the change in the pattern size, and the smaller the change in the pattern when the post-exposure heating (PEB) temperature is low. . That is, since the photosensitive polymer resins represented by Chemical Formulas 1a to 1f having low activation energy should use a low PEB temperature, the extent of acid diffusion due to heat is small, and the magnitude of the line width change is small. It can be seen that the photosensitive polymer resin can reduce the line width change according to the post-exposure heating (PEB) temperature.

Since the photosensitive polymer resin and the chemically amplified photoresist composition having a low activation energy include bulky aliphatic ring hydrocarbons, not only improve dry etching resistance, but also change in line width due to post-exposure heating (PEB) temperature change. By reducing line edge roughness, the semiconductor micropattern can be stably formed even when the post-exposure heating (PEB) temperature is low.

1 is a graph showing development performance according to post-exposure heating (PEB) temperature of a photoresist film formed using the present invention and a conventional chemically amplified photoresist composition.

2 is a graph showing a change in line width according to post-exposure heating (PEB) temperature of a photoresist pattern formed using the present invention and a conventional chemically amplified photoresist composition.

Claims (11)

Chemically amplified photosensitive polymer resin represented by the formula (1). [Formula 1] In Formula 1, R is a methyl or ethyl group, R ^* is hydrogen or a methyl group, R ₁ and R ₂ are each independently hydrogen, methyl or CF ₃ , R ₃ is alkyl having 1 to 20 carbons, 3 to C A cycloalkyl group having 40 cycloalkyl groups or a cycloalkyl group having 5 to 10 carbon atoms including an ether group or an ester group, R ₄ is hydroxyalkyl having 1 to 20 carbon atoms, hydroxyalkyl having 1 to 20 carbon atoms, or an ether group having a halogen substituent Or a cycloalkyl group having 5 to 10 carbon atoms including an ester group. In addition, a, b, c and d is the number of each repeating unit constituting the photosensitive polymer resin, the mole ratio of a: b: c: d is 1 to 40: 1 to 40: 1 to 50: 1 to 50. The photosensitive polymer resin according to claim 1, wherein the weight average molecular weight of the photosensitive polymer resin is 3,000 to 100,000, and the polydispersity is 1.0 to 5.0. The photosensitive polymer resin of claim 1, wherein the photosensitive polymer resin is selected from the group consisting of compounds represented by Formulas 1a to 1g. [Formula 1a] [Formula 1b] [Formula 1c] [Formula 1d] [Formula 1e] [Formula 1f] [Formula 1g] In Formulas 1a to 1g, a, b, c, and d are as defined in Formula 1. A photosensitive polymer resin represented by Chemical Formula 1; Photoacid generators generating acid; And A chemically amplified photoresist composition comprising an organic solvent. The chemically amplified photoresist composition of claim 4, wherein the photoresist composition comprises 1 to 30 wt% of a polymer resin, 0.1 to 20 wt% of a photoacid generator, and the remaining organic solvent. The chemically amplified photoresist composition of claim 4, wherein the photoacid generator is selected from the group consisting of onium salts, organic sulfonic acids, and mixtures thereof. The method of claim 4, wherein the organic solvent is diethylene glycol diethyl ether, methyl 3-methoxy propionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate, cyclohexanone, 2-heptanone, A chemically amplified photoresist composition selected from the group consisting of ethyl lactate and mixtures thereof. The method of claim 4, wherein the photoresist composition further comprises an organic base selected from the group consisting of triethylamine, triisobutylamine, triisooctylamine, diethanolamine, triethanolamine, and mixtures thereof. The amount of base is used in the chemically amplified photoresist composition is 0.01 to 10.00% by weight based on the total photoresist composition. A photosensitive polymer resin represented by Chemical Formula 1; Photoacid generators generating acid; And applying a chemically amplified photoresist composition comprising an organic solvent to the substrate to form a photoresist film. And Exposing the photoresist film in a predetermined pattern, and then heating and developing the exposed photoresist pattern (PEB) and developing the photoresist pattern. The photoresist pattern of claim 9, wherein the exposure process is performed by a process selected from the group consisting of ArF, extreme ultraviolet, vacuum ultraviolet, E-beam, X-ray, ion beam, and immunization lithography. Forming method. The method of claim 9, wherein the development is performed by an aqueous alkali solution.