KR20050002384A - Bi-Layer Photoresist Polymer Containing Silicon and Manufacturing Method of Photoresist Pattern Using the Same - Google Patents

Abstract

PURPOSE: A polymer containing silicon based compound and a method for forming a photoresist pattern using the same are provided to form finely the pattern without collapse by performing etching on a first photoresist layer for ArF using the photoresist pattern. CONSTITUTION: A polymer containing silicon based compound is satisfied with a predetermined chemical formula, wherein R is hydrogen or methyl, R1 is linear or branched chain alkylene of C3 to C10, and R2 to R4 are alkoxy radicals of C1 to C3. The silicon based compound is 3-(trimethoxysilyl)propyl methacrylate.

Description

Bi-Layer Photoresist Polymer Containing Silicon and Manufacturing Method of Photoresist Pattern Using the Same}

The present invention relates to a polymer for a two-layer photoresist comprising a silicon-based compound, a photoresist composition using the polymer and a method of forming a photoresist pattern using the same, and more particularly, in a photolithography process of a semiconductor device. And forming a second resist layer including a silicon-based compound having high etching resistance on the first photoresist layer for ArF, and then etching the first resist layer for ArF using the same, thereby forming a fine photo without collapsing of a pattern. A resist pattern can be formed.

As the semiconductor manufacturing process becomes complicated and the degree of integration of semiconductor devices increases, there is a demand for a method of forming a fine pattern. Thus, it is difficult to obtain such an effect using a photolithography process using a conventional KrF (248 nm) light source. For example, a photolithography process using an ArF (193 nm) light source has been developed.

However, the photoresist material used in the lithography process using the ArF light source has many problems to be commercialized compared to the conventional photoresist material.

The biggest problem is that as the critical dimension (CD) required by high integration of semiconductor devices is reduced, the aspect ratio of the pattern is increased, resulting in the collapse of the photoresist pattern 3 ( See FIG. 1).

In order to prevent this problem, a photoresist pattern having a thickness of 4000 kPa or less was formed, and then an etching process was performed. However, since the photoresist material for ArF that does not contain an aromatic compound such as benzene is less etch resistant than the KrF photoresist material, the etching target layer can be effectively removed when the subsequent dry or wet etching process is performed using the photoresist pattern as an etching mask. Another problem arises that it is impossible to eliminate the circuit formation.

In order to increase the etching resistance of the ArF photoresist material, a method of replacing a backbone with a material containing a carbon ring structure or developing a new etching process has been attempted, but there is a limit to increasing the etching resistance. And there is a disadvantage that the production cost increases.

Recently, in order to solve the above problems, a method of forming a pattern using a two-layer resist, which is performed in a lithography process using a photoresist material containing silicon, has been proposed. However, the photoresist material containing silicon used in the conventional two-layer photoresist process has the disadvantages that the properties of the resist layer, such as the thermal stability of the resist layer and the wettability (wetability) for the developer is lowered as the silicon content increases, overcomes this problem. There is an urgent need for the development of excellent photoresist materials.

Accordingly, the present inventors form a layer having a high etching resistance on the ArF photoresist in order to overcome the above problems, and then etching the ArF photoresist layer using the same, thereby forming a pattern to prevent the pattern collapse phenomenon It is an object to provide a method.

1A is a pattern diagram formed using a conventional resist.

2A to 2D are cross-sectional views illustrating a method of forming a photoresist pattern in the present invention.

<Brief description of the main parts of the drawing>

1, 21: substrate 3: conventional photoresist pattern

23: first photoresist layer 23-1: first photoresist pattern

25: second photoresist layer 25-1: second photoresist pattern

27: photomask

In order to achieve the above object, the present invention provides a polymer for a two-layer photoresist represented by a compound of formula (1) containing silicon.

[Formula 1]

Where

R is hydrogen or methyl,

R ₁ is C ₃ to C ₁₀ linear or branched alkylene,

R ₂ , R ₃ and R ₄ are C ₁ to C ₃ alkoxy groups.

At this time, the compound of Formula 1 has a long chain (chain) form to prevent the sterile hindrance (end group) between the terminal group, it is easy to prepare a polymer.

The compound of Formula 1 is preferably 3- (trimethoxysilyl) propyl methacrylate (3- (trimethoxysilyl) propyl methacrylate).

When the silicon atoms contained in the terminal group of Chemical Formula 1 are subjected to a subsequent O ₂ plasma etching process on the lower ArF photoresist layer, the silicon atoms are combined with oxygen atoms and cured while being formed into glass in the form of a silicon oxide film. . Since the hardened layer has high etching resistance, the ArF photoresist pattern may serve as an etching mask on the ArF photoresist pattern when the etching layer is etched by an etching process using a subsequent CF ₄ plasma gas. do.

Therefore, when the resist for ArF is formed to be less than 4000 kPa in order to lower the aspect ratio, not only the pattern collapse may be prevented, but also the etching resistance is increased by the hardened layer to form a lower etching layer pattern. Since it becomes easy, there is an advantage that a high resolution pattern can be formed.

In addition, the polymer for a two-layer photoresist comprising the compound of Formula 1 preferably comprises a repeating unit of the formula (6) further comprising one or more compounds of the comonomers of formulas (2) to (5). .

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

Where

R is hydrogen or methyl,

R ₁ is C ₃ to C ₁₀ linear or branched alkylene,

R ₂ , R ₃ and R ₄ are C ₁ -C ₃ alkoxy groups,

R ₅ is OH, H or C ₁ -C ₁₀ alkyl,

R ₆ is CH ₃ or H,

R ₇ is OH, H or C ₁ -C ₁₀ alkyl,

a: b: c: d: e is 5-15 mol%: 20-40 mol%: 20-35 mol%: 15-25 mol%: 0-10 mol%.

The polymerization repeating unit of Chemical Formula 6 is preferably the following Chemical Formula 7.

[Formula 7]

Where

a: b: c: d is 15 mol%: 30 mol%: 30 mol%: 25 mol%.

The polymer of the present invention may be prepared using a radical polymerization reaction, wherein the radical polymerization is performed by a bulk polymerization solution or a solution polymerization reaction.

In the case of the solution polymerization, the polymerization solvent is selected from the group consisting of tetrahydrofuran, cyclohexanone, cyclopentanone, dimethylformamide, dimethyl sulfoxide, methyl ethyl ketone, dioxane, benzene, toluene and xylene, and the like. It is preferable to use a solvent or a mixed solvent.

The polymerization reaction was carried out with 2,2'-azobisisobutyronitrile (AIBN), benzoyl peroxide, acetyl peroxide, lauryl peroxide, t-butylperacetate, t-butylhydroperoxide and di-t-butyl Peroxide, etc., in the presence of a polymerization initiator selected from the group consisting of.

In addition, the present invention includes a two-layer photoresist composition comprising a polymer for a two-layer photoresist comprising a compound of the formula (1), a photoacid generator and an organic solvent.

The photoacid generator may be used as long as the compound can generate an acid by light, US 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (1996. 11.28), EP 0 794 458 (September 10, 1997) EP 0 789 278 (August 13, 1997), US 5,750,680 (May 12, 1998), US 6,051,678 (April 18, 2000), GB 2,345,286 A (August 7, 2000), US 6,132,926 (October 17, 2000), US 6,143,463 (Nov. 7, 2000), US 6,150,069 (November 21, 2000), US 6.180.316 B1 (January 30, 2001) ), US 6,225,020 B1 (May 1, 2001), US 6,235,448 B1 (May 22, 2001) and US 6,235,447 B1 (May 22, 2001) and the like, and mainly include sulfide-based or onium salt-based compounds use. In particular, phthalimidotrifluoromethane sulfonate, dinitrobenzyltosylate, n-decyl disulfone and naphthylimidotrifluoromethane having low absorbance at 157 nm and 193 nm Preference is given to using those selected from the group consisting of naphthylimido trifluoromethane sulfonate, together with diphenylurodoxyl hexafluorophosphate, diphenylurodoxyl hexafluoro arsenate, diphenylurodoxyl hexafluoro antimonate, Diphenylparamethoxyphenylsulfonium triflate, diphenylparatoluenylsulfonium triflate, diphenylparaisobutylphenylsulfonium triflate, triphenylsulfonium hexafluoro arsenate, triphenylsulfonium hexafluoro Antimonate, triphenylsulfonium triflate and dibutylnaphthylsulfonium triple It can also be used for the photo acid generator selected from the group consisting of bytes, and are preferably used in an amount of 0.01 to 5wt% with respect to the photoresist polymer. When the photoacid generator is used in an amount of 0.01wt% or less, the sensitivity of the photoresist to light is weak. When the photoacid generator is used at 5wt% or more, the photoacid generator absorbs a lot of ultraviolet rays and generates a large amount of acid, thereby obtaining a pattern having a bad cross section.

In addition, the organic solvent can be used in any one, US 5,212,043 (May 18, 1993), WO 97/33198 (September 12, 1997), WO 96/37526 (Nov. 28, 1996), EP 0 794 458 (October 10, 1997) EP 0 789 278 (August 13, 1997), US 5,750,680 (May 12, 1998), US 6,051,678 (April 18, 2000), GB 2,345,286 A (2000. 7. 5), US 6,132,926 (October 17, 2000), US 6,143,463 (11/7/2000), US 6,150,069 (11/21/2000), US 6.180.316 B1 (January 30, 2001), US 6,225,020 B1 (2001. 5) 1), US 6,235,448 B1 (May 22, 2001) and US 6,235,447 B1 (May 22, 2001) and the like, preferably diethylene glycol diethyl ether, methyl 3- A methoxy propionate, ethyl 3-ethoxy propionate, propylene glycol methyl ether acetate, cyclohexanone, 2-heptanone, etc. can be used individually or in mixture.

In the present invention,

(a) forming a first resist layer on the etched layer;

(b) forming a second resist layer on the first photoresist layer by using a two-layer photoresist composition comprising the silicon compound of the present invention;

(c) forming a second photoresist pattern by performing exposure and development processes on the second resist layer; And

(d) performing a O ₂ plasma etching process on the first photoresist layer using the second photoresist pattern as an etching mask to form a two-layer photoresist pattern having a second photoresist pattern formed on the first photoresist pattern. It provides a method of forming a photoresist pattern comprising the step of forming.

The method may further include, after the step (d), forming the etched layer pattern using the CF ₄ plasma etching process on the lower etched layer using the two-layer resist as an etch mask.

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

Referring to FIG. 2A, a first ArF photoresist layer 23 is formed on the etched layer 21, and the second photoresist layer 25 is formed on the second ArF photoresist layer. Form sequentially.

In this case, the etched layer is formed using one material selected from an oxide film, a nitride film, a polycrystalline silicon film, a borophosphosilicate glass (BPSG), aluminum, tungsten, cobalt, an organic diffuse reflection prevention material, or a metal such as titanium.

The first ArF photoresist layer is preferably formed to a thickness of 4000 GPa or less, preferably 3000 to 4000 GPa, and the second photoresist layer is preferably 500 to 1500 GPa, more preferably 1000 GPa. Do.

The method may further include a soft baking process after the first and second photoresist layer forming steps.

The first resist layer can be any general photoresist material for ArF, for example, any chemically amplified polymer, US 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 5,750,680 (May 12, 1998), US 6,051,678 (April 2000) 18), GB 2,345,286 A (July 5, 2000), US 6,132,926 (October 17, 2000), US 6,143,463 (November 7, 2000), US 6,150,069 (November 21, 2000), US 6.180.316 B1 (January 30, 2001), US 6,225,020 B1 (May 1, 2001), US 6,235,448 B1 (May 22, 2001) and US 6,235,447 B1 (May 22, 2001) and the like. In particular, poly (t-butyl bicyclo [2.2.1] hept-5-ene-2-carboxylate / 2) in which the cycloolefin-based comonomers are polymerized by addition to maintain the ring structure without breaking the ring structure. Hydroxyethyl bicyclo [2.2.1] hept-5-ene-2-carboxylate / bicyclo [2.2.1] hept-5-ene-2-carboxylic acid / maleic anhydride) and the like Can be.

In this case, the photoresist material for ArF may be used instead of the photoresist material for KrF.

Referring to FIG. 2B, an exposure process and a development process using the photomask 27 are performed on a predetermined region of the second photoresist layer 25.

The light source of the exposure process is performed using an exposure energy of 1 to 100mJ / cm ² using ArF, KrF, Extreme Ultra Violet (EUV), Vacuum Ultra Violet (VUV), E-beam, X-ray or ion beam. It is desirable to be.

Referring to FIG. 2C, an O ₂ plasma dry etching process is performed on the first photoresist layer using the second photoresist pattern 25-1 obtained by the lithography process as an etching mask.

The _two- layer photoresist pattern having the second photoresist pattern 25-1 formed on the one photoresist pattern 23-1 is formed by the O ₂ plasma etching process.

At this time, the second photoresist pattern 25-1 is cured by the reaction of silicon inside the second photoresist pattern 25-1 during the O ₂ plasma etching process to form a silicon oxide film.

Referring to FIG. 2D, the CF ₄ plasma dry etching process may be performed on the etched layer 21 using the first photoresist pattern formed on the second photoresist pattern 25-1 hardened by the etching process as an etching mask. To form a predetermined semiconductor element pattern.

In the pattern forming method, a photoresist layer including only the silicon compound of the present invention without a first photoresist layer is formed below, and then an etching process is performed to bond surfaces of the silicon compound and the etching layer in an O ₂ plasma treatment process. Since the reaction in the composition breaks the bond in the composition and the photoresist layer is stripped, the photoresist polymer of the present invention is preferably used in a two-layer photoresist pattern process.

In addition, the polymer and the composition including the silicon compound as described above may not only have thermal stability of the photoresist layer, but also form a stable photoresist pattern having high wettability to a developer.

Hereinafter, the present invention will be described in detail by examples. However, the examples are only to illustrate the invention and the present invention is not limited by the following examples.

Example 1 Synthesis of Polymer for Two-Layer Photoresist of Formula 7

5 g of 3- (trimethoxysilyl) propyl methacrylate, 1 g of 2-hydroxymethyl methacrylate, 4 g of methyl 5-norbornene-2-carboxylate, 3 g of maleic hydride and 2,2′-azobis 0.13 g of isobutyronitrile was dissolved in 20 ml of tetrahydrofuran, and the solution was slowly stirred at 67 ° C. for about 24 hours under an argon atmosphere. The reaction solution was precipitated in methanol, filtered, washed with methanol several times, reduced pressure and dried at room temperature to obtain the compound of formula 7 (yield 50%).

Example 2 Formation of Two-Layer Photoresist Pattern

(Step 1)

The polymer (1 g) prepared in Example 1 and the photoacid generator phthalimidotrifluoromethanesulfonate (0.01 g) were dissolved in propylene glycol methyl ethyl acetate (PGMEA) (8 g), and then filtered through a 0.20 μm filter to photoresist. A composition was obtained.

(Step 2)

After forming the first photoresist layer using the photoresist composition for ArF on the etched layer, spin-coated the composition obtained in the step 1 above, and soft-baking for 90 seconds in an oven or hot plate at 140 ° C. 2 photoresist layer was formed. The second photoresist layer was exposed to light using an ArF laser exposure apparatus and then baked again at 140 ° C. for 90 seconds. The baked wafer was immersed in a 2.38wt% TMAH aqueous solution for 90 seconds to develop a second photoresist L / S pattern of 0.15 탆 (see FIG. 2B).

(Step 3)

2-layer photoresist L having a second photoresist pattern formed on top of the first photoresist pattern of 0.15 탆 by performing an O ₂ plasma etching process on the first resist layer using the second photoresist pattern formed in step 2 as an etching mask. A / S pattern was formed (see FIG. 2C).

As described above, the photoresist composition of the present invention is formed on the ArF photoresist pattern having a low aspect ratio, thereby compensating the etching resistance of the ArF photoresist pattern, and thus a stable pattern during the subsequent etching process. Can be formed, and the yield of an element can be improved.

Claims (22)

A photoresist polymer comprising a compound of formula (1). [Formula 1] Where R is hydrogen or methyl, R ₁ is C ₃ to C ₁₀ linear or branched alkylene, R ₂ , R ₃ and R ₄ are C ₁ to C ₃ alkoxy groups. The method of claim 1, The photoresist polymer is a photoresist polymer, characterized in that used in the two-layer photoresist process. The method of claim 1, Said compound is 3- (trimethoxysilyl) propyl methacrylate (3- (trimethoxysilyl) propyl methacrylate). The method of claim 1, The photoresist polymer is a photoresist polymer, characterized in that it comprises a repeating unit of the formula (6) comprising at least one compound of the comonomers of formulas (2) to (5). [Formula 2] [Formula 3] [Formula 4] [Formula 5] [Formula 6] Where R is hydrogen or methyl, R ₁ is C ₃ to C ₁₀ linear or branched alkylene, R ₂ , R ₃ and R ₄ are C ₁ -C ₃ alkoxy groups, R ₅ is OH, H or C ₁ -C ₁₀ alkyl, R ₆ is CH ₃ or H, R ₇ is OH, H or C ₁ -C ₁₀ alkyl, a: b: c: d: e is 5-15 mol%: 20-40 mol%: 20-35 mol%: 15-25 mol%: 0-10 mol%. The method of claim 4, wherein Polymerization repeating unit of Formula 6 is a photoresist polymer, characterized in that the formula (7). [Formula 7] Where a: b: c: d is 15 mol%: 30 mol%: 30 mol%: 25 mol%. The method of claim 1, The photoresist polymer is a single or mixed solvent selected from the group consisting of tetrahydrofuran, cyclohexanone, cyclopentanone, dimethylformamide, dimethyl sulfoxide, methyl ethyl ketone, dioxane, benzene, toluene and xylene. A polymer for photoresists, which is prepared by solution polymerization to be used. The method of claim 6, The solution polymerization is 2,2'-azobisisobutyronitrile (AIBN), benzoyl peroxide, acetyl peroxide, lauryl peroxide, t-butylperacetate, t-butylhydroperoxide and di-t-butyl A photoresist polymer, characterized in that carried out in the presence of a polymerization initiator selected from the group consisting of peroxides. A photoresist composition, comprising a photoresist polymer, a photoacid generator and an organic solvent according to claim 1. The method of claim 8, The photoacid generators include phthalimidotrifluoromethane sulfonate, dinitrobenzyltosylate, n-decyl disulfone, and naphthylimidotrifluoromethanesulfonate. trifluoromethane sulfonate) composition for photoresists, characterized in that selected from the group consisting of. The method of claim 9, In addition to the photoacid generator, diphenyl iodo hexafluorophosphate, diphenyl iodo hexafluoro arsenate, diphenyl iodo hexafluoro antimonate, diphenyl paramethoxyphenylsulfonium triflate, diphenyl paratoluene Nylsulfonium triflate, diphenylparaisobutylphenylsulfonium triflate, triphenylsulfonium hexafluoro arsenate, triphenylsulfonium hexafluoro antimonate, triphenylsulfonium triflate and dibutylnaphthylsulfonium A composition for photoresist, characterized in that used together with the one selected from the group consisting of triflate. The method of claim 8, The photoresist composition is a photoresist composition, characterized in that used in 0.01 to 5wt% relative to the photoresist polymer. The method of claim 8, The organic solvent is diethylene glycol diethyl ether, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methyl ether acetate, cyclohexanone and 2-heptanone. A composition for photoresist, characterized in that selected from the group consisting of. (a) forming a first photoresist layer on the etched layer; (b) forming a second photoresist layer on the first photoresist layer by using the photoresist composition of claim 8; (c) performing a process of exposing and developing the second photoresist layer to form a second photoresist pattern; And (d) performing a O ₂ plasma etching process on the first photoresist layer using the second photoresist pattern as an etching mask to form a two-layer photoresist pattern having a second photoresist pattern formed on the first photoresist pattern. Forming a photoresist pattern comprising the step of forming. The method of claim 13, After the step (d), using the two-layer photoresist pattern as an etch mask to form an etched layer pattern using a CF ₄ plasma etching process for the lower etched layer further comprising the step of forming a photoresist pattern . The method of claim 13, And the first photoresist layer is formed to a thickness of 3000 to 4000 GPa. The method of claim 13, And the second photoresist layer is formed to a thickness of 500 to 1500 kPa. The method of claim 13, After the first and second photoresist layer forming step, the method further comprises a soft bake process. The method of claim 13, And the first resist layer is formed of a resist material for ArF. The method of claim 13, The first resist layer is poly (t-butyl bicyclo [2.2.1] hept-5-ene-2-carboxylate / 2-hydroxyethyl bicyclo [2.2.1] hept-5-ene-2- Carboxylate / bicyclo [2.2.1] hept-5-ene-2-carboxylic acid / maleic hydride). The method of claim 13, The etched layer is formed using an oxide film, a nitride film, a polycrystalline silicon film, borophosphosilicate glass (BPSG), aluminum, tungsten, cobalt, titanium, and an organic anti-reflective material selected from the group consisting of a photoresist pattern Forming method. The method of claim 13, The exposure process is a photoresist pattern forming method using a light source of Ar, KrF, Extreme Ultra Violet (EUV), Vacuum Ultra Violet (VUV), E-beam, X-ray or ion beam. The method of claim 21, The exposure process is a photoresist pattern forming method, characterized in that carried out with an exposure energy of 1 to 100mJ / cm ² .