KR20020058336A - Polymer for photoresist and prepartion thereof - Google Patents

Abstract

PURPOSE: Provided are a polymer for photoresist which can be used in submicron patterning procedure during a semiconductor manufacturing process, and a method for producing the same. CONSTITUTION: The polymer, which is poly(styrene-hydroxystyrene-phenethyl styryl acetal) copolymer, has a structure represented by formula 1(wherein X and Y represent mole fraction of 0.01-0.95, and Z is mole fraction of 0.01-0.98). The copolymer has molecular weight of 3000-15000. The copolymer is produced by the steps of (i) dissolving styrene monomer of formula 6, hydroxy styrene monomer of formula 7, and phenethyl styryl acetal monomer of formula 8, and (ii) adding initiators to the obtained material to polymerize the material under nitrogen or argon atmosphere.

Description

POLYMER FOR PHOTORESIST AND PREPARTION THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoresist polymer used in an ultrafine pattern forming process in a semiconductor device process, and particularly includes a protecting group having a large activation energy, and thus soft bake to a photoresist (SOFT BAKE: SOB). Or to prevent excessive deprotection of the protecting group and the generation of gas, which may occur during exposure, thereby preventing contamination of the exposure lens and coating equipment by the gas and reducing the thickness loss of the photoresist. The present invention relates to a novel photoresist polymer capable of minimizing, stabilizing and yielding a frequency element manufacturing process, and a method of manufacturing the same and a pattern forming method using the same.

In the process of forming an ultrafine pattern in a semiconductor device process, a chemically amplified photoresist made of acetal-based or T-BOC-based polymer and the like has been mainly used. In the case of using such a photoresist, once exposure to the photoresist is made, a protecting group having a low activation energy from the polymer for photoresist is deprotected due to the energy supplied by the exposure, and then the The deprotected protecting group is developed by aqueous alkali solution, whereby a pattern is formed.

However, when the above pattern forming process is performed using a conventional photoresist made of an acetal-based or T-BOC-based polymer, since the protecting group bound to the polymer has too low activation energy, it is necessary to form the pattern. Compared to this, excessive deprotection may occur, which causes severe thickness damage of the photoresist during exposure and post exposure baking (PEB) required for pattern formation, resulting in a pattern formation process margin. This reduced problem may appear, and the problem of reducing the etching etch rate may also occur in the subsequent etching process step.

In addition, due to such excessive deprotection, gases such as polyvinyl hydroxy styrene, carbon dioxide, isobutene, etc. may be generated. The gas contaminates the exposure lens and the coating equipment, thereby lowering the efficiency and life of the exposure lens. There has been a problem that may have an inefficient effect on the manufacturing process of a stable semiconductor device.

Due to the problems of the conventional photoresist as described above, excessive deprotection of the protecting group contained in the photoresist polymer does not occur, thereby preventing the loss of thickness of the photoresist and preventing generation of gas due to excessive deprotection. There is an urgent need for a photoresist made of a polymer capable of preventing contamination of the exposure lens and coating equipment by the gas.

Accordingly, an object of the present invention is to provide a novel photoresist polymer that can be used in an ultra-fine pattern forming process and a method for manufacturing the same, thereby preventing excessive deprotection that may occur in the pattern forming process. It is to prevent the damage of the photoresist thickness according to the result, to thereby produce a semiconductor device having a more stable ultra-fine pattern shape.

1 is a photograph showing a pattern formed by applying the photoresist pattern forming method according to the present invention having the polymer of Example 1,

2 is a photograph showing a pattern formed by applying the photoresist pattern forming method according to the present invention having the polymer of Example 2,

3 is a photograph showing a pattern formed by applying the photoresist pattern forming method according to the present invention with the polymer of Example 5.

In order to achieve the above object, the present invention provides a photoresist polymer having a structure represented by the following Chemical Formula 1.

(Poly [styrene-hydroxy styrene-phenethyl styryl acetal] copolymer)

(Poly [styrene-hydroxy styrene- (naphthylethyl) styryl acetal copolymer)

(Poly [styrene-hydroxy styrene-nofil styryl acetal] copolymer)

(Poly [styrene-hydroxy styrene-t-butyl styryl acetal] copolymer)

(Poly [styrene-hydroxy styrene-t-butyl styryl acetal-phenethyl styryl acetal] copolymer)

In each of the above formulas, W, X, and Y each represent a mole fraction of 0.01 to 0.95, and Z represents a mole fraction of 0.01 to 0.98.

As shown in Chemical Formulas 1 to 5, the photoresist polymer according to the present invention introduces bulky protecting groups such as phenethyl group, naphthyl ethyl group, nophil group, and t-butyl group into the hydroxy styrene monomer. In order to deprotect the same bulky protecting group, high activation energy is required, and deprotection does not occur even at the soft bake temperature applied to the existing acetal or T-BOC-based photoresist, and exposure to the photoresist and PEB are performed. In this process, since excessive deprotection does not occur than necessary to form a pattern, gas generated by the excessive deprotection can be minimized.

The molecular weight of the polymer having a structure of Formulas 1 to 5 is preferably 3000 to 15000.

The polymers of Chemical Formulas 1 to 5 may be prepared by dissolving the monomers constituting each polymer in an organic solvent, and then adding a polymerization initiator to the resultant to react in a nitrogen or argon atmosphere. Organic solvents may be used, preferably toluene or tetrahydrofuran (THF). In the manufacturing process, in the preparation of the polymer of Chemical Formula 1, styrene (Formula 6), hydroxy styrene (Formula 7), phenethyl styryl acetal (Formula 8) as monomers In the case of Formula 2, styrene, hydroxy styrene, (naphthylethyl) styryl acetal (Formula 9) is used, and in the case of Formula 3, styrene, hydroxy styrene, nofil sty Reyl acetal (Formula 10) is used, and in the case of Formula 4, styrene, hydroxy styrene, t-butyl styryl acetal (Formula 11) is used, and in preparing the polymer of Formula 5, styrene, hydroxy styrene , t-butyl styryl acetal, phenethyl styryl acetal are preferably used as monomers. Each of the preferred monomers has a structure such as the following Chemical Formulas 6 to 11.

(Styrene monomer)

(Hydroxy styrene monomer)

(Phenethyl Styryl Acetal Monomer)

((Naphthylethyl) styryl acetal monomer)

(Nofil Styryl Acetal Monomer)

(t-butyl styryl acetal monomer)

In addition, the polymerization reaction as described above may be performed at a reaction temperature of 60-70 ° C., and a general radical initiator may be used as the polymerization initiator, but preferably AIBN (azobisisobutyronitrile) may be used. have.

In addition, the present invention provides a photoresist liquid obtained by dissolving the polymer of Formulas 1 to 5 in an organic solvent and then adding a photoacid generator to the resultant. As the organic solvent, a conventional organic solvent may be used, but preferably methyl 3-methoxy propionate or ethyl 3-ethoxy propionate may be used, and the photoacid generator may be a sulfide-based or onium compound. Preference is given to using substances comprising salt-based functional groups. Such photoacid generators include diphenyl iodo hexafluoro phosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxy phenyl triflate, diphenyl paratoluenyl Triflate, diphenylsulfonium hexafloor phosphate, triphenylsulfonium hexafloor arsenate, triphenylsulfonium hexafloor antimonate, triphenylsulfonium triflate, dibutylnaphthyl sulfonium triflate Preference is given to using one substance or a mixture of two or more selected from the group consisting of.

The present invention also comprises the steps of applying the photoresist liquid according to the present invention on the etched layer; After the process, the soft baking process; Exposing and then developing the formed photoresist to form a photoresist pattern; It provides a photoresist pattern forming method comprising the step of forming a pattern of the layer to be etched using the formed photoresist pattern as an etching mask.

In the method of forming the photoresist pattern, the photoresist liquid is preferably coated so as to have a thickness of 2500 kPa to 3000 kPa. desirable.

Further, in the pattern forming process, the baking process (PEB) may be additionally included after the exposure, and the baking process is preferably performed at 70 to 200 ° C.

In the pattern forming process, the exposure process is performed in a group consisting of deep ultraviolet (DUV), electron beam (E-beam), X-ray and ion beam (i-beam) including KrF, ArF, EUV as a light source. It is preferred to use one or more selected, and it is preferred to proceed with an exposure energy of 0.1 to 10 mJ / cm ² . Therefore, the photoresist according to the present invention is preferably used for ion beam, KrF, ArF, 157 nm EUV, electron beam, or X-ray.

The pattern forming method according to the present invention can be applied to the process of forming a line, a space, or a contact hole pattern during a process of a semiconductor device. Therefore, the present invention provides a semiconductor device, which is manufactured including the pattern forming method.

Hereinafter will be described in more detail with reference to preferred embodiments of the present invention. However, the following examples are not intended to limit the scope of the present invention, but are presented by way of example only.

Example 1

Synthesis of Poly [styrene-hydroxy styrene-phenethyl styryl acetal] terpolymer (Formula 1)

0,5 mol of styrene 0.05 N, 0.5-0.8 mol of hydroxy styrene monomer and 0.4-0.9 mol of phenethyl styryl acetal monomer were placed in a 500 ml round flask containing 150 ml of tetrahydrofuran or toluene and dissolved, and the initiator AIBN was added to the resultant. 0.5 to 10 g was added, followed by reaction for 4 to 24 hours at a temperature of about 60 to 70 ° C. under nitrogen or argon atmosphere.

The resultant is then cooled to room temperature and then poured into a beaker with 500 ml of ethyl ether or hexane to precipitate the reaction. When the precipitate is filtered and dried at 30 ° C., a poly [styrene-hydroxy styrene-phenethyl styryl acetal] terpolymer of formula 1 may be obtained.

Example 2

Synthesis of Poly [styrene-hydroxy styrene- (naphthylethyl) styryl acetal] terpolymer (Formula 2)

After dissolving 0.05 Negine 0,5 mol of styrene and 0.05 to 0.8 mol of hydroxy styrene monomer and 0.4 to 0.9 mol of (naphthylethyl) styryl acetal monomer in a 500 ml round flask containing tetrahydrofuran or 150 ml of toluene, the resulting product was dissolved. 0.5 to 10 g of an initiator AIBN was added thereto, followed by reaction for 4 to 24 hours at a temperature of about 60 to 70 ° C. under a nitrogen or argon atmosphere.

The resultant is then cooled to room temperature and then poured into a beaker with 500 ml of ethyl ether or hexane to precipitate the reaction. When the precipitate is filtered and dried at 30 ° C., a poly [styrene-hydroxy styrene- (naphthylethyl) styryl acetal] terpolymer of formula 2 can be obtained.

Example 3

Synthesis of Poly [styrene-hydroxy styrene-nophil styryl acetal] terpolymer (Formula 3)

0,5 mol of styrene 0.05 N, 0.5-0.8 mol of hydroxy styrene monomer and 0.4-0.9 mol of nofil styryl acetal monomer were dissolved in a 500 ml round flask containing 150 ml of tetrahydrofuran or toluene, and then the initiator AIBN was added to the resultant. 0.5 to 10 g is added, followed by reaction for 4 to 24 hours at a temperature of about 60 to 70 ° C. under nitrogen or argon atmosphere.

The resultant is then cooled to room temperature and then poured into a beaker with 500 ml of ethyl ether or hexane to precipitate the reaction. When the precipitate is filtered and dried at 30 ° C., a poly [styrene-hydroxy styrene-nofil styryl acetal] terpolymer of formula 3 may be obtained.

Example 4

Synthesis of Poly [styrene-hydroxy styrene-t-butyl styryl acetal] terpolymer (Formula 4)

After dissolving 0.05 Negine 0,5 mole of styrene and 0.05 to 0.8 mole of hydroxy styrene monomer and 0.4 to 0.9 mole of t-butyl styryl acetal in a 500 ml round flask containing 150 ml of tetrahydrofuran or toluene, the resultant was added to the initiator AIBN. 0.5 to 10 g was added, followed by reaction for 4 to 24 hours at a temperature of about 60 to 70 ° C. under nitrogen or argon atmosphere.

The resultant is then cooled to room temperature and then poured into a beaker with 500 ml of ethyl ether or hexane to precipitate the reaction. When the precipitate is filtered and dried at 30 ° C., a poly [styrene-hydroxy styrene-t-butyl styryl acetal] terpolymer of formula 4 can be obtained.

Example 5

Synthesis of Poly [styrene-hydroxy styrene-t-butyl styryl acetal-phenethyl styryl acetal] quaternary copolymer (Formula 5)

500 ml round flask with 0.05 Negative 0,5 mol of styrene and 0.05 to 0.8 mol of hydroxy styrene monomer, 0.4 to 0.9 mol of t-butyl styryl acetal and 0.4 to 0.9 mol of phenethyl styryl acetal monomer 150 ml of tetrahydrofuran or toluene After dissolving in the solution, 0.5 to 10 g of initiator AIBN was added to the resultant, and then reacted at a temperature of about 60 to 70 ° C. for 4 to 24 hours under an atmosphere of nitrogen or argon.

The resultant is then cooled to room temperature and then poured into a beaker with 500 ml of ethyl ether or hexane to precipitate the reaction. When the precipitate is filtered and dried at 30 ° C., a poly [styrene-hydroxy styrene-t-butyl styryl acetal-phenethyl styryl acetal] quaternary copolymer of Chemical Formula 5 can be obtained.

Example 6

Preparation of Photoresist Liquid

10 g of the poly [styrene-hydroxy styrene-phenethyl styryl acetal] copolymer synthesized in Example 1 was dissolved in 50 g of methyl 3-methoxypropionate or ethyl 3-ethoxypropionate solvent. The resultant was added with 0.01-1 g of phenyl sulfonium triflate or dibutyl naphthyl sulfonium triflate as a photo-acid generator, stirred, and filtered through a 0.10 μm filter to obtain a photoresist solution.

Also in the case of the polymer synthesized in Example 2-5, the photoresist liquid according to the present invention can be produced in the same manner as described above.

Example 7

Photoresist Pattern Formation Method

After coating the photoresist liquid formed in the same manner as in Example 6 on the wafer, the soft bake was performed for 90 seconds at a temperature of 90 ℃, exposed, then baked (PEB) at 110 ℃ for 90 seconds again , The resultant was developed in a 2.38wt% tetramethylammonium hydroxyalkali aqueous solution to obtain a fine pattern having a shape as shown in FIGS. 1 to 3.

Example 8

Thickness Measurement of Coating Film

Acetal photoresist, which has been used in the past, was coated on a wafer and subjected to soft baking to measure the thickness of the wafer, which was 4600 mW. However, after exposure and PEB were carried out on the resultant, the thickness was 3800 mW, resulting in a large thickness loss. This occurred.

On the other hand, as a result of the above process using the photoresist according to Example 1 of the present invention, as shown in Table 1, there was almost no thickness loss from 4800Å before exposure to 4600Å after PEB.

In addition, even when the above process was performed with the photoresists of Examples 2 and 3 of the present invention, as shown in Table 1 below, there was no thickness loss.

Resist form Film thickness (after softbaking) Film thickness (after exposure / PEB) Film thickness reduction rate (%) Conventional Acetal Resist 4600 yen 3800 yen 18 Resist of Example 1 4800 yen 4600 yen 4.2 Resist of Example 2 5600 yen 5300 yen 5.4 Example 3 'resist 4100 yen 3900 yen 4.9

As described above, the present invention provides a polymer for photoresist having a bulky group having a high activation energy as a protecting group, thereby preventing excessive deprotection of the protecting group that may occur in the ultra-fine pattern forming process of the semiconductor device process, It is possible to minimize the thickness damage of the photoresist and the generation of gas due to the excessive deprotection, and to prevent contamination of the exposure lens and the coating lens by the generated gas.

Therefore, by using the polymer according to the present invention as a photoresist in the ultrafine pattern forming step, a stabilized ultrafine pattern can be obtained, whereby the semiconductor element process can be stabilized and the yield of the product can be improved.

Claims (30)

A poly [styrene-hydroxy styrene-phenethyl styryl acetal] copolymer having a structure of formula (1) (Formula 1) In the above formula, X and Y represent a mole fraction of 0.01 to 0.95, and Z represents a mole fraction of 0.01 to 0.98. The copolymer of claim 1, wherein the copolymer has a molecular weight of 3000 to 15000. By dissolving the styrene monomer of the formula (6), the hydroxy styrene monomer of the formula (7) and the phenethyl styryl acetal monomer of the formula (8) in an organic solvent, and then adding an initiator to the resultant to polymerize under nitrogen or argon atmosphere, Method of preparing a copolymer of the formula (1). (Formula 6) (Formula 7) (Formula 8) A poly [styrene-hydroxy styrene- (naphthylethyl) styryl acetal] copolymer having a structure of formula (2). (Formula 2) In the above formula, X and Y represent a mole fraction of 0.01 to 0.95, and Z represents a mole fraction of 0.01 to 0.98. The copolymer according to claim 4, wherein the copolymer has a molecular weight of 3000 to 15000. After dissolving a styrene monomer of Formula 6, a hydroxy styrene monomer of Formula 7 and a (naphthylethyl) styryl acetal monomer of Formula 9 in an organic solvent, an initiator was added to the resultant to polymerize under nitrogen or argon atmosphere. By reacting, a method of preparing the copolymer of the formula (2). (Formula 6) (Formula 7) (Formula 9) A poly [styrene-hydroxy styrene-nofil styryl acetal] copolymer having a structure of formula (3) (Formula 3) In the above formula, X and Y represent a mole fraction of 0.01 to 0.95, and Z represents a mole fraction of 0.01 to 0.98. 8. The copolymer according to claim 7, wherein the copolymer has a molecular weight of 3000 to 15000. After dissolving the styrene monomer of the formula (6), the hydroxy styrene monomer of the formula (7) and the nofil styryl acetal monomer of the formula (10) in an organic solvent, by adding an initiator to the resultant and polymerized under nitrogen or argon atmosphere, A process for preparing the copolymer of formula (3). (Formula 6) (Formula 7) Formula 10 A poly [styrene-hydroxy styrene-t-butyl styryl acetal] copolymer having a structure of the following formula (4). (Formula 4) In the above formula, X and Y represent a mole fraction of 0.01 to 0.95, and Z represents a mole fraction of 0.01 to 0.98. 11. The copolymer according to claim 10, wherein the copolymer has a molecular weight of 3000 to 15000. After dissolving the styrene monomer of the formula (6), the hydroxy styrene monomer of the formula (7) and the t-butyl styryl acetal monomer of the formula (11) in an organic solvent, by adding an initiator to the resultant by polymerization reaction under nitrogen or argon atmosphere , To prepare a copolymer of the formula (4). (Formula 6) (Formula 7) Formula 11 A poly [styrene-hydroxy styrene-t-butyl styryl acetal-phenethyl styryl acetal] copolymer having a structure of formula (5): (Formula 5) In the above formula, W, X, and Y represent a mole fraction of 0.01 to 0.95, and Z represents a mole fraction of 0.01 to 0.98. The copolymer according to claim 13, wherein the copolymer has a molecular weight of 3000 to 15000. After dissolving a styrene monomer of Formula 6, a hydroxy styrene monomer of Formula 7, a t-butyl styryl acetal monomer of Formula 11, and a phenethyl styryl monomer of Formula 8, in an organic solvent, an initiator was added to the resultant. Method of preparing a copolymer of the formula (5) by adding and polymerizing under nitrogen or argon atmosphere. (Formula 6) (Formula 7) (Formula 11) (Formula 8) The production method according to any one of claims 3, 6, 9, 12, and 15, wherein the organic solvent uses toluene or tetrahydrofuran. The production method according to any one of claims 3, 6, 9, 12, and 15, wherein azobisisobutyronitrile (AIBN) is used as the initiator. 16. The process according to any one of claims 3, 6, 9, 12 and 15, wherein the polymerization reaction is carried out at a temperature of 60 to 70 ° C. A method of preparing a photoresist liquid by dissolving a copolymer of any of Formulas 1 to 5 in an organic solvent and then adding a photoacid generator to the resultant. A photoresist prepared using the manufacturing method of claim 19. 20. The method of claim 19, wherein the organic solvent is methyl 3-methoxypropionate or ethyl 3-ethoxy propionate. 20. The method of claim 19, wherein the photoacid generator is a material comprising a sulfur-based or onium salt-based functional group. 20. The method of claim 19, wherein the photoacid generator is diphenyl iodo hexafluoro phosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxy phenyl triflate, diphenyl Paratoluenyl triflate, diphenylsulfonium hexafloor phosphate, triphenylsulfonium hexafloor arsenate, triphenylsulfonium hexafloor antimonate, triphenylsulfonium triflate, dibutylnaphthyl sulphate A process characterized by using one material selected from the group consisting of phosphon triflate or a mixture of two or more. Applying the photoresist liquid of claim 19 on the etched layer; After the process, soft baking to form a photoresist film; Exposing the formed photoresist film and then developing the photoresist pattern to form a photoresist pattern; And And forming a pattern of the layer to be etched using the formed photoresist pattern as an etching mask. 25. The method of claim 24, wherein the photoresist solution is coated to have a thickness of 2500 to 3000 mm 3. The method of claim 24, wherein the soft bake process is performed at a temperature of 90-180 ° C. for 30 to 300 seconds. 25. The method of claim 24, further comprising the step of performing a bake process after said exposure. The method of claim 27, wherein the baking process is performed at 70 to 200 ° C. 29. 29. The method of claim 24, 25, 27, 28, wherein the exposing step proceeds with an exposure energy of 0.1-10 mJ / cm ² . A semiconductor device comprising the method of forming a photoresist pattern of claim 24.