KR0178332B1 - Copolymers of n-(camphorsulfonyloxy) maleimide and preparation of producing thereof - Google Patents

Abstract

The present invention relates to a copolymer having an alternating structure of one or two selected from N-camphorsulfonyloxymaleimide, a maleimide compound, a styrene compound, and a methacrylic acid ester compound as a unit of a copolymer, and a method for producing the same. It is about. The copolymers of the present invention exhibit good film formation and low light absorption and are very suitable polymers for resist applications.

Description

Copolymer of N (N) -camphorsulfonyloxymaleimide and its preparation method

In the present invention, a copolymer having an alternating structure of N-camphorsulfonyloxymaleimide (hereinafter referred to as CmpSOMI) and one or two of the following compounds as a unit structure of the copolymer: And a method for producing the same.

Wherein X is (+)-10-camphorsulfonyl, (-)-10-camphorsulfonyl, or (+)-10-camphorsulfonyl, Y is -H, -OH, -COOBu-t,- OCOOBu-t, -OBu-t, or -C ₆ H ₄ OCOOBu-t, Z is -OCOOBu-t, -CH ₃ , -Cl, substituted at the para or meta position of the benzene ring -OCOCH ₃ , -Si (CH ₃ ) ₃ , -OH, or -H.

Chemically amplified photoresist materials that are currently being actively researched for the manufacture of ultra-high density semiconductors include photoacid generators that generate acid by short-wavelength ultraviolet exposure. Onium salts that are typically used as photoacid generators include ammonium salts, iodonisium salts, and sulfonium salts. These onium salts have disadvantages such as thermal instability and low solubility, and the metals they contain are microcircuit processing processes. May contaminate the semiconductor device. Therefore, in order to replace this, the development of non-ionic organic photoacid generator is in progress, and among them, organic sulfonic acid ester has been studied a lot.

Whereas the existing photoresist material is a two-component or ternary system in which a photo-acid generator and an acid-reactive substance are combined, the present inventors have studied and reported a one-component resist polymer in which the photo-acid generator and the acid reactor are bonded to the same polymer chain. have. For example, N-tosyloxy maleimide [Chem. Mater. 1994, 6, 1452], N-methanesulfonyloxymaleimide [N- (methanesulfonyl) maleimide] and N-trifluoromethanesulfonyloxymaleimide [N- (triflouromethanesulfonyloxy) maleimide] [Korean Patent Application No. 20037 (1994)] was newly synthesized, and it was confirmed that toluenesulfonic acid, methanesulfonic acid, and trifluorosulfonic acid were generated with high efficiency when these copolymers were exposed to ultraviolet rays, respectively. In addition, these monomers were copolymerized with monomers having an acid reactive group to study the one-component resist characteristics of the copolymer (Korean Patent Application No. 20036 (1994)). Since the photo-acid generator does not need to be mixed separately in the one-component resist, problems caused by low solubility of the photo-acid generator in the two-component or third-order resist or lack of compatibility with other components contained in the resist can be overcome.

As described above, the maleimide compound described above can easily introduce a functional group to the N-position of the maleimide, and can easily synthesize various functional maleimide polymers using the N-substituted maleimide monomer. have. The electron deficient maleimide monomer has a high polymer conversion rate due to its high reactivity in the radical copolymerization reaction with an electron-rich monomer such as a styrene derivative, and the resulting polymer has an alternating structure in which the maleimide monomer and the styrene monomer are alternately bonded. To form. Terpolymers can be synthesized with the use of third comonomers to synthesize binary copolymers with comonomers of various chemical structures for the purpose of altering the properties of the maleimide polymer to impart desired properties. terpolymer) can be easily synthesized.

In addition, since the maleimide polymer has a high glass transition temperature due to the succinimide structure, it has low light absorption in the far ultraviolet region and good film forming ability. The application potential as a photoresist material is very large. In particular, polymers in which an acid-decomposable protecting group is introduced at the N-position of maleimide are deprotected at relatively low temperatures (about 100 ° C.) in the presence of an acid, thereby causing a significant change in solubility. The maleimide polymer may be applied to various fields requiring heat resistance in addition to photoresist.

Based on this fact, the present inventors have N-terminated butoxycarbonylmaleimide (t-N-substituted with tert-butoxycarbonyl (t-BOC) and tert-butoxy (t-BuO) protecting groups, respectively. BOCMI) and N-tert-butoxymaleimide (t-BuOMI) were newly synthesized and the resist properties of the polymers were investigated (Korean Patent No. 070225 (1994), 084289 (1995), 086663). (1995), 082594 (1995)]. There are also patents relating to monomer synthesis of N- (tertiarybutoxycarbonyloxy) maleimide (t-BOCOMI) and to resist applications of polymers [Korean Patent Application Nos. 38063 (1994) and 38064. (1994)].

In the present invention, unlike the previous maleimide copolymer, a copolymer having an alternating structure with other comonomers can be obtained by using CmpSOMI having a camphorsulfonyloxy group bonded to the N-position of the maleimide as a monomer. The copolymer according to the present invention has a heat resistance of 200 ° C. or more, which is an important required property of a resist material, and exhibits a low light absorption of 0.3 / µm or less at 248 nm, making it a very suitable polymer for resist applications.

Accordingly, it is an object of the present invention to provide a copolymer having an alternating structure of one or two of CmpSOMI and the compounds presented above as the unit structure of the copolymer.

Another object of the present invention is to provide a method for producing a copolymer according to the present invention. The copolymer production method of the present invention comprises radical copolymerization of one or two of CmpSOMI, a maleimide compound (Y-MI), a styrene compound (Z-St), and a methacrylic acid ester compound.

Another object of the present invention is to provide a monomer CmpSOMI used to prepare the copolymer of the present invention.

Hereinafter, the present invention will be described in more detail.

CmpSOMI used as a monomer of the copolymer of the present invention is a novel compound (+) CmpSOMI, (-) CmpSOMI, or a racemate (±) CmpSOMI in which both are mixed in the same amount, particularly in the N-position of maleimide Among the camphor sulfonyloxy groups, the camphor group has an alkyl ring, so that the camphor group may have dry etching characteristics, which is an essential requirement of the resist, and also have very low light absorption in the far ultraviolet region. Since the camphor group has optical isomers of (+) and (-) bodies, when the crosslinked polymer of either optically active (+) CmpSOMI or (-) CmpSOMI is produced and exposed, the corresponding sulfonic acid is released. Where the group is removed, there is a possibility of application as a molecular recognition template polymer that recognizes only optical isomers having the same optical code as the removed camphor group. That is, the copolymer of the present invention can be obtained from CmpSOMI having a high sensitivity, high resolution, and heat resistance as a monomer and having a function of acid generation during exposure. The chemical structure of (+) CmpSOMI having a positive optical sign of CmpSOMI is shown below.

The monomer CmpSOMI of the present invention has been reported for the incorporation of structural formula (II) [Bull. Chem. Soc. Jpn., 1971, 44, 1084], wherein the combination reacted with (1S)-(+)-10-camphorsulfonylchloride to introduce a camphorsulfonyl group at the N-position of the copolymer (IIIa). N-[(1S)-(+)-10-camphorsulfonyloxy] -3,6-epoxy-1,2,3,6-tetrahydrophthalimide was synthesized and then heated under reduced pressure from the copolymer ( (+) CmpSOMI of formula (Ia) in a yield of about 50% by retro-Diels-Alder reaction.

Optical isomers have almost identical chemical and physical properties other than their conformation and optical activity, so that (1R)-(-)-10-camphorsulfonyl chloride or (±) -10-camphorsulfonyl chloride is used to form (+ In the same way as for CmpSOMI, synthesis of (-) CmpSOMI or racemic chain (±) CmpSOMI is possible. In the present invention, the synthetic method as a whole, the mass production is possible because the raw material is derived from natural acids.

As the comonomer having another structure of the present invention, one or two of maleimide compounds (Y-MI), styrene compounds (Z-St) and methacrylic acid ester compounds are selected. Y-MI having an acid reactive group in Y-MI is Nt-butyloxycarbonylmaleimide (t-BOCMI), Nt-butoxymaleimide (t-BuOMI), Nt-butyloxycarbonyloxymaleimide (t- BOCOMI) and Nt-butyloxycarbonyloxyphenylmaleimide (t-BOCOPMI), and the deprotected form of Y-MI includes maleimide (MI) and N-hydroxymaleimide (HOMI). have. Acid-reactive Z-St in Z-St includes t-butyloxycarbonyloxystyrene (t-BOCSt) having a t-BOC substituent in the para or meta position, and includes styrene (St) as a general Z-St. And methyl styrene (MeSt), chloro styrene (ClSt), acetoxy styrene (AcOSt), trimethylsilyl styrene (SiSt), and hydroxy styrene (HOSt) having a substituent in the para or meta position. T-butyl methacrylate (t-BMA) is included as a methacrylic acid ester compound.

In the copolymer of the present invention having an alternating structure of such monomers and comonomers, the structure of CmpSOMI is 0.1-1.0 in molar ratio relative to the entire copolymer. The reason for such a range suggestion is as follows. If an acid-reactive group is present in the copolymer, even a small amount of acid may be deprotected, and thus, CmpSOMI may be included in less than 10%. In addition, since the CmpSOMI structure itself can increase the solubility in aqueous alkali solution by acid generation, a copolymer of a deprotected form of comonomer with a higher molar ratio of CmpSOMI, or a homopolymer made only of CmpSOMI, may be used as a one-component resist application. This is possible. That is, depending on the chemical structure and content of the comonomer, the optimum content of CmpSOMI may vary within the ranges given above.

Representative 1: 1 alternating copolymer P [(+) CmpSOMI / t-BOCt] synthesized according to the present invention is stable up to about 150 ° C. in thermogravimetric analysis (TGA) and deprotection of t-BOC groups above 150 ° C. And a weight loss of 25%, corresponding to the generation of carbon dioxide and 2-methylpropene. In the differential thermal analysis (DSC), the polymer exhibits an endotherm corresponding to the deprotection of t-BOC groups at 171 ° C. in the first measurement when observed at room temperature to 200 ° C., followed by deprotection of the same deprotected sample. In the secondary measurement observed after cooling to the temperature again, the glass transition temperature (Tg) is shown at a high temperature of about 245 ° C, and decomposition of the polymer starts at about 270 ° C. Taken together, these thermal analysis results show that the copolymer of the present invention has heat resistance suitable for a microimage forming process before and after deprotection.

Monomers with protecting groups deprotectable by acid and copolymers prepared from CmpSOMI generate camphorsulfonic acid when irradiated with light and deacidification of the polymer occurs by the acid during post-exposure heating. Application is possible with a one-component resist material that does not need to be. In fact, the ultraviolet rays (DUV) of the copolymer containing the monomer combined with the CmpSOMI monomer and the acid reactive group were analyzed by TGA and DSC, and the deprotection temperature was found to be significantly lowered below 100 ° C.

The copolymers of the present invention all exhibit good film forming ability and exhibit light absorption of 0.3 or less per 1 탆 thickness at 248 nm, making the polymer highly suitable for resist applications using an exposure source of 248 nm. The copolymer of the present invention is insoluble in an aqueous alkali solution such as caustic soda and ammonium salt, but soluble in organic solvents such as cyclohexanone and anisole, whereas the deprotected polymer is well soluble in aqueous alkali solution and insoluble in most organic solvents. It appears that the polarity change due to deprotection of the acid reactive protecting group greatly changes the solubility of the polymer.

The applicability as a photoresist to the copolymer of the present invention can be estimated by conventional microimaging formation experiments. Micro-image formation experiments consist of preparing a copolymer solution, rotating coating on a silicon wafer, exposing through a photomask (250 nm wavelength), and heating at around 100 ° C. to develop an organic solvent such as an aqueous alkali solution or anisole. In this microimage formation test the copolymer P [(+) CmpSOMI / t-BOCSt] forms a positive or negative microimage. Other copolymers of the present invention also form microimages under similar conditions.

As a special case, a copolymer having a deprotected structure in advance, for example, a copolymer P [(+) CmpSOMI / HOSt having a hydroxystyrene unit, is a resist material that can be developed only by exposure without the need for a post-exposure heating process. The application is possible as. In other words, the copolymer P [(+) CmpSOMI / HOSt] before exposure is insoluble in aqueous alkali solution, but the structure is changed to P [(+) CmpSOMI / MI / HOSt] as the CmpSOMI unit is partially decomposed by exposure to generate camphorsulfonic acid. Therefore, it becomes soluble in aqueous alkali solution which is a developing solution. Since the polymer has a deprotected structure in advance, it has high sensitivity and high adhesion to a substrate as compared with a polymer having no hydroxystyrene unit.

The copolymer of the present invention is prepared by copolymerizing a monomer and a comonomer shown above according to a conventional radical polymerization method using a radical polymerization initiator. As the radical polymerization initiator, azobisisobutyronitrile (AIBN) which is generally used is used. Dioxane is used as the solvent. The polymerization reaction is carried out under a nitrogen atmosphere at a temperature of 50-60 ℃, the molecular weight of the copolymer can be controlled by the amount of initiator or solvent. In general, the copolymer has a conversion ratio of 85% or more, and a copolymer produced by polymerizing maleimide-based monomers and styrene-based monomers in a 1: 1 molar ratio is an alternating copolymer in which the two types of monomer molar ratios are 1: 1 according to elemental analysis. It is confirmed that it is a structure.

Representatively, the production of the monomer (+) CmpSOMI, the preparation of the copolymer, and the formation of a micro image using the copolymer will be described in detail below.

Example 1

[Production of (+) CmpSOMI (Ia)]

Flask containing 48.00 g (0.12 mol) of N-[(1S)-(+)-10-camphorsulfonyloxy] -3,6-epoxy-1,2,3,6-tetrahydrophthalimide (IIIa) Pyrolysis was carried out under reduced pressure. The resulting furan was collected from a cold trap installed between the flask and the aspirator. After the pyrolysis of about 1 hour it was confirmed that the bubble was stopped, acetone was added to remove the insoluble matter and recrystallized with a mixed solvent of ethyl acetate and hexane to give 18.00g (0.055mol, 45% yield) of (+) CmpSOMI. The melting point of (+) CmpSOMI was measured at 102-103 ° C.

In proton spectroscopy, two protons of double bonds were identified as single peaks (6.86 ppm), and two protons of -SCH ₂ -were identified as doublets (3.51, 3.58, 3.90, and 3.98 ppm), respectively, Protons were identified as multiplets (1.48-2.36 ppm) and six protons of the methyl group were identified as singlets (0.91 and 1.12 ppm), respectively. The double bond in the CH absorption band for 3160, 3100 cm ^-1 in infrared spectroscopic analysis, the imide absorption band at 1760 cm ^-1, it was confirmed the absorption band of the sulfone from 1190cm ^-1. From carbon 13-proton spectroscopy, two methyl groups have 17.90 ppm carbon, -C- (CH ₃ ) ₂ carbon 23.68 ppm, and cyclohexanone rings have 25.13, 40.65, 41.16, 46.50, 48.99 ppm -SCH ₂ The carbon of-was found to be 56.56 ppm, the carbon of the maleimide ring double bond, 131.37 ppm, the carbonyl carbon of the maleimide 162.22 ppm, and the carbonyl carbon of the cyclohexanone ring at 211.68 ppm. Elemental analysis showed 51.50% carbon, 5.23% hydrogen, 3.92% nitrogen, 9.45% sulfur, 29.90% oxygen, and theoretically calculated 51.36% carbon, 5.24% hydrogen, 4.28% nitrogen, 9.79% sulfur. The molecular formula of C ₁₄ H ₁₇ NSO ₆ was confirmed by almost identical with 29.33% of oxygen.

Example 2

Preparation of Copolymer P [(+) CmpSOMI / t-BOCSt]

1.65 g (5.0 mmol) of (+) CmpSOMI monomer, 0.42 g (5.0 mmol) of pt-butyloxycarbonyloxystyrene (t-BOCSt), 32.8 mg (0.2 mmol) of azobisisobutyronitrile (AIBN) in the polymerization vessel 5 ml of dioxane was added and dissolved, and the mixture was polymerized under a nitrogen stream for 3 hours while maintaining 55 ° C using an oil bath. Dioxane was added to the viscous polymer solution to lower the viscosity, which was then added dropwise to methanol to precipitate. The precipitate was filtered and dried to obtain 2.44 g (89% conversion) of the copolymer P [(+) CmpSOMI / t-BOCSt].

The elemental analysis showed that carbon was present at 59.4%, hydrogen at 6.13%, nitrogen at 2.41%, and sulfur at 5.85%, and the result was 59.2% of carbon, assuming a 1: 1 alternate structure of (+) CmpSOMI and t-BOCOSt. It was confirmed that the copolymer P [(+) CmpSOMI / t-BOCSt] had an alternating structure because it almost coincided with 6.08% of hydrogen, 2.56% of nitrogen, and 5.86% of sulfur. Thermal analysis of this copolymer showed a 25% weight loss at 171 ° C, corresponding to deprotection of t-BOC groups.

Example 3

[Preparation of Copolymer P [(+) CmpSOMI / HOSt]

1.64 g (5.0 mmol) of (+) CmpSOMI monomer, 0.60 g (5.0 mmol) of p-hydroxystyrene (HOSt), 32.8 mg (0.2 mmol) of azobisisobutyronitrile were added to the polymerization vessel, and 6.5 ml of dioxane was added thereto. After dissolving, polymerization was carried out under a nitrogen stream for 18 hours while maintaining a temperature of 55 ° C. using an oil bath. Dioxane was added to the viscous polymer solution to lower the viscosity, followed by dropwise addition to methanol to precipitate. The precipitate was filtered and dried to obtain 1.16 g (52% conversion) of copolymer P [(+) CmpSOMI / HOSt]. The elemental analysis revealed that carbon was present in 59.0%, 5.63% in hydrogen, 3.13% in nitrogen, and 7.16% in sulfur, and this result was 58.8% carbon, which assumes a 1: 1 alternating structure of (+) CmpSOMI and HOSt. It was confirmed that the copolymer P [(+) CmpSOMI / HOSt] had an alternating structure from almost 5.53%, 3.03% of nitrogen, and 7.12% of sulfur.

Example 4

[Preparation of Terpolymer P [(+) CmpSOMI / t-BOCMI / HOSt]]

1.65 g (5.0 mmol) of (+) CmpSOMI monomer, 0.98 g (5.0 mmol) of N-tertiaryburoxycarbonylmaleimide (t-BOCMI), 1.20 g (10.0 mmol) of p-hydroxystyrene (HOSt) 65.6 mg (0.4 mmol) of azobisisobutyronitrile (AIBN), a radical polymerization initiator, was added and dissolved in 7.6 ml of dioxane, followed by polymerization under nitrogen stream for 2 hours while maintaining the temperature at 55 ° C. using an oil bath. . Dioxane was added to the viscous polymer solution to lower the viscosity, which was then added dropwise into methanol to precipitate. The precipitate was filtered and dried to obtain 2.34 g (61% conversion) of the copolymer P [(+) CmpSOMI / t-BOCMI / HOSt]. .

Example 5

[Formation of fine image]

5-20% by weight of the copolymer P [(+) CmpSOMI / t-BOCSt] prepared in Example 2 was dissolved in cyclohexanone and filtered through an ultrafine filter to prepare a chemically amplified resist solution. The resist solution was spin-coated on a silicon wafer to prepare a thin film having a thickness of 0.5-1 μm. The sample wafer is prebaked for 1-3 minutes on a 90 ° C. hotplate, exposed to 250 nm wavelength of ultraviolet light using an ultraviolet device, and post-processed for 1-3 minutes at a temperature of 80-120 ° C. -exposure baking was immersed in an aqueous solution of trimethylammonium hydroxide (2.38% by weight) and anisole for 30 to 180 seconds. As a result, when the developer was an aqueous solution of trimethylammonium hydroxide, the exposed portion was dissolved to form a positive microscopic image of submicron, and in the case of anisole, the non-exposed portion was dissolved to form a negative image.

Claims (3)

A copolymer having, as the unit structure of the copolymer, N-camphorsulfonyloxymaleimide of the following formula and one or two alternating structures of the following formula; Wherein X is (+)-10-camphorsulfonyl, (-)-10-camphorsulfonyl, or (+)-10-camphorsulfonyl, Y is -H, -OH, -COOBu-t,- OCOOBu-t, -OBu-t, or -C ₆ H ₄ OCOOBu-t, Z is -OCCBu-t, -CH ₃ , -Cl, -OCOCH ₃ , -Si substituted at the para or meta position of the benzene ring (CH ₃ ) ₃ , -OH, or -H. The copolymer according to claim 1, wherein the N-camphorsulfonyloxymaleimide unit in the alternating structure is 0.1-1.0 in molar ratio relative to the entire copolymer. Method for producing a copolymer of claim 1 consisting of radical copolymerization by mixing N-camphorsulfonyloxymaleimide of the following formula and one or two of the following formula; Wherein X is (+)-10-camphorsulfonyl, (-)-10-camphorsulfonyl, or (+)-10-camphorsulfonyl, Y is -H, -OH, -COOBu-t,- OCOOBu-t, -OBu-t, or -C ₆ H ₄ OCOOBu-t, Z is -OCOOBu-t, -CH ₃ , -Cl, substituted at the para or meta position of the benzene ring -OCOCH ₃ , -Si (CH ₃ ) ₃ , -OH, or -H.