KR100315726B1 - Imide monomer for silylation photoresist, copolymer resin using the same, and method for producing the pattern of photoresist using the same resin - Google Patents

Abstract

PURPOSE: An imide monomer for silylation photoresist, a copolymer resin using the same, and a method for producing the pattern of photoresist using the same resin are provided, thereby forming micro-patterns using chemically amplified photoresist. CONSTITUTION: A photoresist copolymer is characterized by containing a portion represented by formula(2), wherein R is p(t-butoxycarboxylate)phenyl, 2-(t-butoxycarboxylate)ethyl or 3-(t-butoxycarboxylate)propyl; n is polymerization degree of 10 to 2000. A process for preparing the photoresist copolymer comprises the steps of: dissolving at least one imide monomer of formula(1) in dimethyl formamide; adding a polymerization initiator into the imide monomer-dissolved solution and reacting them under nitrogen or argon atmosphere at 60 to 75 deg. C for 2 to 24 hours; and forming the photoresist copolymer containing the portion of formula(2) from the reaction product.

Description

Imide-based monomer for silylation photoresist, copolymer resin using this monomer and method for producing photoresist pattern using this resin

The present invention relates to an imide monomer for a silicide photosensitive film, a photoresist copolymer using the monomer and a method for producing a photosensitive film pattern using the copolymer. Specifically, by using a chemically amplified photoresist (chemically amplified photoresist) containing a heat-resistant imide to form a fine pattern of 0.1 ㎛ or less by using an ultraviolet light source such as KrF or ArF, according to the semiconductor device It relates to a technology that enables high integration.

Generally, in the manufacturing process of a semiconductor device, in order to form the semiconductor device pattern of a predetermined shape, the photosensitive film pattern is used as an etching mask. In order to obtain a photoresist pattern, a photoresist is applied on a semiconductor substrate, the exposed photoresist is selectively exposed, and then a developing process is performed to form a desired photoresist pattern on the etched layer.

In preparing a photoresist pattern by using a conventional general silylation process, the photoresist (see 15 in FIG. 1) is made of a photosensitive material and a novolak resin. Therefore, when baking is performed after exposure, an alcohol group is formed in the exposed portion. After baking, the silylation is performed with a silylation agent, and the silylation agent used is mainly one having an N-Si bond such as hexamethyldisilazane or tetramethyl disilazane. use. Since the N-Si bond has a weak bonding force, the N-Si bond reacts with the ROH of the resin to form a RO-Si bond. The silicon combined with the resin forms a silicon oxide film during a dry develop process using an O ₂ plasma, and the lower end of the portion remains as it is after development to form a pattern. Therefore, when the pattern is formed in this way, the silicide occurs in the exposed portion, which is very advantageous for forming contact holes.

However, in the method of forming the photoresist pattern by the conventional silylation process, when the KrF excimer laser is used, it is impossible to form a fine pattern of 0.1 μm or less. However, the photoresist film was exposed at a low exposure energy of 10 mJ / cm 2 or less, but the photosensitive film was not sufficiently exposed at such a low energy, so that a pattern could not be formed. In addition, there are problems such as roughness of the pattern, which is a problem of the silicide process itself, or high integration of the semiconductor device due to lack of resolution.

Therefore, the TSI process (top surface image) process has been proposed as an attempt to solve this problem, but even using this TSI process, it is impossible to form a line / space pattern of less than 0.10 μm using the existing KrF excimer laser, resulting in high integration of the device. There is a problem that hinders.

Accordingly, the present inventors have conducted numerous studies and experiments to solve the above-mentioned problems of the prior art, and as a result, by using imides having high heat resistance in the photoresist resin, the in-process temperature accompanying the TSI process is high. The heat resistance to withstand the post exposure bake process and the silylation process can be ensured, and by using a chemically amplified photosensitive film, the lens of the exposure equipment is not damaged by the ArF light when the ArF light source is used. It has been surprisingly found that resolution is possible even at low energy (10 mJ / cm 2 or less) and the present invention has been completed.

Figure 1a to 1e is a photosensitive film pattern manufacturing process chart using the sililation process according to the present invention.

<Description of Symbols for Major Parts of Drawings>

11 wafer 13 etched layer

15 photosensitive film 17 exposure mask

19: silylation film 21: silicon oxide film

The 1st aspect of this invention relates to the novel imide type monomer for salicylation photosensitive film represented by following General formula (1).

[Formula 1]

In the above formula,

R represents p- (t-butoxycarboxylate) phenyl, 2- (t-butoxycarboxylate) ethyl or 3- (t-butoxycarboxylate) propyl.

The second aspect of the present invention relates to a photoresist copolymer for silicide comprising a moiety represented by the following formula (2) prepared from the imide monomer of formula (1).

[Formula 2]

In the above formula,

R represents p- (t-butoxycarboxylate) phenyl, 2- (t-butoxycarboxylate) ethyl or 3- (t-butoxycarboxylate) propyl,

n is a number of 10-2000 as polymerization degree.

The third aspect of the present invention relates to a method for producing a photosensitive film pattern using the photoresist copolymer resin for silylation of the formula (2).

In addition, the fourth aspect of the present invention relates to a semiconductor device manufactured using the photosensitive film pattern described above.

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

Preferred examples of the imide-based photoresist monomer of Formula 1 according to the present invention include p- (t-butoxycarboxylate) phenyl maleimide, 2- (t-butoxycarboxylate) ethyl maleimide or 3- (t -Butoxycarboxylate) propyl maleimide and the like.

The imide-based photoresist monomer of Formula 1 according to the present invention is imidized in the presence of acetic anhydride after reacting amino phenol, ethanolamine or 3-aminopropanol with maleic anhydride. Can be prepared.

Specifically, amino phenol, ethanolamine, or 3-aminopropanol is dissolved in a purified dimethylformamide (DMF) solvent, and then maleic anhydride is added and stirred for 5 to 10 hours. After completion of the reaction, acetic anhydride and sodium acetate were added and reacted at 60 to 100 ° C. for 20 to 30 hours for imidization. Subsequently, the by-product glacial acetic acid and the solvent are removed using a rotary evaporator, water and tetrahydrofuran (THF) are added thereto, and the organic layer is separated using a separatory funnel. 5 wt% aqueous tetramethylammonium hydroxide (TMAH) solution was added to p-maleimide phenyl acetate, 2-maleimide ethyl acetate, or 3-maleimide propyl acetate, which are the products in the organic layer, at 50 to 70 ° C. for 5 to 15 hours. After reaction, the mixture is separated to obtain p-maleimide phenol, 2-maleimide ethanol or 3-maleimide-1-propanol, and the like is dissolved in dimethylformamide (DMF), followed by di-t-butoxy carbonate and potassium t. Add butoxide and stir for 12 to 16 hours. After completion of the reaction, the solvent was removed by a still, and a mixed solvent of n-hexane and ethyl acetate was used as a developing solvent to obtain an imide-based photoresist monomer of the formula (1).

The photoresist copolymer for silylation according to the present invention is specifically poly [p- (t-butoxycarboxylate) phenyl maleimide], poly [2- (t-butoxycarboxylate) ethyl malee Mid] or poly [3- (t-butoxycarboxylate) propyl maleimide] moiety.

The photoresist copolymer for siliculation of formula (2) according to the present invention dissolves at least one imide monomer and other suitable photoresist monomers represented by the formula (1) in an organic solvent such as dimethylformamide (DMF), It can be prepared by polymerization in the presence of the same polymerization initiator.

Specifically, p- (t-butoxycarboxylate) phenyl maleimide, 2- (t-butoxycarboxylate) ethyl maleimide or 3- (t-butoxycarboxylate) propyl maleimide or the like After dissolving the de-based monomer in a DMF solvent, azobisisobutyronitrile (AIBN) is added as a polymerization initiator and reacted for 4 to 24 hours at a temperature of 60 to 75 ° C. in a nitrogen or argon atmosphere. The resin produced by the reaction is precipitated and dried with ethyl ether or hexane to obtain a photoresist copolymer of the formula (2).

The present invention also provides a photoresist composition containing the photoresist copolymer, organic solvent and photoacid generator of the present invention described above.

The organic solvent may be any organic solvent that is generally used, but is preferably methyl 3-methoxy propionate.

In addition, the photoacid generator may use sulfide-based or onium salt-based compounds, preferably triphenylsulfonium triflate or dibutylnaphthyl sulfonium triflate.

The photosensitive film pattern according to the present invention can be prepared through the following steps (a) to (g):

(a) dissolving at least one photoresist copolymer comprising the moiety represented by Formula 2 in a solvent and mixing with a photoacid generator to form the photoresist composition described above;

(b) forming an etching target layer on the substrate on which the pattern is to be formed;

(c) forming a photosensitive film by applying the photoresist composition on the etched layer;

(d) selectively exposing the photosensitive film;

(e) forming a silylation film on the exposed portion of the photosensitive film,

(f) dry developing the photosensitive film with O ₂ plasma to form a photosensitive film pattern, and

(g) forming an etched layer pattern by etching the etched layer using the photoresist pattern as an etching mask.

Referring to the drawings, a method of manufacturing a photosensitive film pattern using a silylation process according to the present invention is wound as follows.

As shown in FIGS. 1A to 1E, first, an etching target layer 13 to form a pattern is formed on the wafer 11, and the silicide copolymer resin of Formula 2 is included on the etching target layer 13. After the photosensitive film 15 is formed, the photosensitive film 15 is selectively exposed to an ArF light source using the exposure mask 17 (see FIG. 1A), and then baked. At this time, the exposed portion of the photosensitive film 15 generates acid, and the non-exposed portion does not generate acid. (See FIG. 1B). The photoacid generator mainly uses sulfide-based or onium salt-based compounds, and preferably triphenylsulfonium triflate or dibutylnaphthyl sulfonium triflate.

Subsequently, hexamethyldisilazane or tetramethyldisilazane is used as the silylation agent to silylate the exposed portion of the photosensitive film 15 to form the silicide film 19 (see Fig. 1C).

Thereafter, when the photoresist film 15 is developed by a dry development process using O ₂ plasma, a silicon oxide film 21 is formed on the silicide film 19 which is an exposed portion of the photoresist film 15 due to the dry phenomenon. To become resistant to oxygen plasma, and the non-exposed portion of the photosensitive film 15 is removed to form a photosensitive film pattern (see FIG. 1D).

Thereafter, the etched layer 13 exposed using the photoresist pattern using an etching mask is etched to form an etched layer pattern (see FIG. 1E).

Hereinafter, although this invention is demonstrated concretely based on an Example, it should not be understood that the technical scope of this invention is limited to these.

Example 1 Synthesis of p- (t-butoxycarboxylate) phenylmaleimide (Formula 3)

[Formula 3]

54.5 g of amino phenol was dissolved in 200 g of purified dimethylformamide (DMF), and 49 g of maleic anhydride was added thereto and stirred for 8 hours. After completion of the reaction, acetic anhydride 250g and sodium acetate 15g were added and reacted at 80 ° C. for 24 hours for imidization. Next, by-product glacial acetic acid and the solvent are removed by rotary distillation, water and tetrahydrofuran (THF) are added thereto, and the organic layer is separated using a separatory funnel. 100 g of a 5 wt% aqueous TMAH solution was added to p-maleimide phenyl acetate, the product in the organic layer, and reacted at 60 ° C. for 10 hours, followed by separation to obtain p-maleimide phenol, and 95 g of the p-maleimide phenol to 400 g of DMF. After melting, 87 g of di-t-butoxy carbonate and 10 g of potassium t-butoxide were added thereto, followed by stirring for 14 hours. After completion of the reaction, the solvent was removed by a still, and 86.9 g of p- (t-butoxycarboxylate) phenyl maleimide (Formula 3) was obtained using a mixed solvent of n-hexane and ethyl acetate as a developing solvent. (Yield 60%).

Example 2: Synthesis of 2- (t-butoxycarboxylate) ethylmaleimide (Formula 4)

[Formula 4]

31 g of ethanolamine was dissolved in 200 g of purified dimethylformamide, and 49 g of maleic anhydride was added thereto, followed by stirring for 8 hours. After completion of the reaction, acetic anhydride 250g and sodium acetate 15g were added and reacted at 80 ° C. for 24 hours for imidization. Then, by-product glacial acetic acid and the solvent are removed by a rotary distiller, water and THF are added, and an organic funnel is separated using a separatory funnel. 100 g of 5 wt% TMAH aqueous solution was added to 2-maleimide ethyl acetate, which is a product in the organic layer, and reacted at 60 ° C. for 10 hours to separate 2-maleimide ethanol, and 70 g of 2-maleimide ethanol was added to 400 g of DMF. After melting, 87 g of di-t-butoxy carbonate and 10 g of potassium t-butoxide were added thereto, followed by stirring for 14 hours. After completion of the reaction, the solvent was removed by a distillation, and 77 g of 2- (t-butoxycarboxylate) ethyl maleimide (Formula 4) was obtained using a mixed solvent of n-hexane and ethyl acetate as a developing solvent (yield: 64 %).

Example 3: Synthesis of 3- (t-butoxycarboxylate) propylmaleimide (Formula 5)

[Formula 5]

Dissolve 38 g of 3-aminopropanol in 200 g of purified dimethylformamide (DMF), add 49 g of maleic anhydride, and stir for 8 hours. After completion of the reaction, acetic anhydride 250g and sodium acetate 15g were added and reacted at 80 ° C for 24 hours for imidization. Then, by-product glacial acetic acid and the solvent are removed by a rotary distiller, water and THF are added, and an organic funnel is separated using a separatory funnel. 100 g of 5 wt% TMAH aqueous solution was added to 3-maleimide propyl acetate, which is the product in the organic layer, and reacted at 60 ° C. for 10 hours to separate 3-maleimide-1-propanol to obtain 3-maleimide-1-propanol. 77 g The mixture was dissolved in 400 g of DMF, 87 g of di-t-butoxy carbonate and 10 g of potassium t-butoxide were added thereto, followed by stirring for 14 hours. After completion of the reaction, the solvent was removed by a distiller, and 79 g of 3- (t-butoxycarboxylate) propyl maleimide (Formula 5) was obtained using a mixed solvent of n-hexane and ethyl acetate as a developing solvent (yield: 62 %).

Examples 4 to 6 below are methods for obtaining photoresist copolymers using the monomers synthesized in Examples 1 to 3. In this case, the monomer added in the polymerization process may further include a monomer required in addition to the monomers of Examples 1 to 3 to perform a polymerization reaction to prepare a photoresist copolymer.

Example 4: Synthesis of Poly [p- (t-butoxycarboxylate) phenylmaleimide] copolymer resin (Formula 6)

[Formula 6]

After dissolving 50 g of p- (t-butoxycarboxylate) phenyl maleimide obtained in Example 1 in a DMF solvent, 1 g of azobisisobutyronitrile (AIBN) was added thereto and a temperature of 67 ° C. in a nitrogen or argon atmosphere was used. The reaction is carried out for 10 hours. The resin produced by the reaction was precipitated and dried with ethyl ether or hexane to obtain 35 g of a poly [p- (t-butoxycarboxylate) phenyl maleimide] copolymer resin (Formula 6) (yield: 70%).

Example 5: Synthesis of Poly [2- (t-butoxycarboxylate) ethylmaleimide] copolymer resin (Formula 7)

[Formula 7]

After dissolving 50 g of 2- (t-butoxycarboxylate) ethyl maleimide obtained in Example 2 in DMF solvent, the same procedure as in Example 4 was carried out to give poly [2- (t-butoxycarboxylate) Ethyl maleimide] 36 g of a copolymer resin (Formula 7) was obtained (yield: 72%).

Example 6: Synthesis of Poly [3- (t-butoxycarboxylate) propylmaleimide] copolymer resin (Formula 8)

[Formula 8]

After dissolving 50 g of 3- (t-butoxycarboxylate) propyl maleimide obtained in Example 3 in DMF solvent, the same procedure as in Example 4 was carried out to obtain poly [3- (t-butoxycarboxylate) 35 g of propyl maleimide] copolymer resin (Formula 8) was obtained (yield: 69%).

Example 7 Preparation of Photosensitive Film Pattern

10 g of each of the three copolymer resins obtained in Examples 4 to 6 was dissolved in 40 g of methyl 3-methoxy propionate solvent, and then triphenylsulfonium triflate or dibutylnaphthyl sulfonium was used as a photoacid generator. 0.2-1 g of triflate was added and stirred, followed by filtration with a 0.10 µm filter to obtain three types of photoresist compositions.

Subsequently, an etching target layer is formed on the wafer, and a pretreatment step of spraying hexamethyldisilazane (HMDS) on the surface thereof is performed. Here, the process may be a dehydration process through a high temperature bake process, but in order to maximize the treatment effect, the hydrophilic state of the Si-OH type hydrophilic state is hydrophobic on the surface of the etching layer using HMDS. By changing to a state, it is possible to improve the adhesion between the surface of the etched layer and the photoresist film and to prevent the photoresist coating defect.

Thereafter, one of the photoresist compositions obtained above is spin coated on the etched layer to form a photosensitive film. In this case, the photosensitive resin is already because it contains a de has a heat resistance to withstand the exposure and the baking step in a subsequent process, using a chemically amplified photoresist layer, so the resolution in a small amount of energy of about 0.1~10mJ / cm ² It is possible.

The photoresist film is then exposed using an exposure mask. In this case, the exposure process is performed using ArF, KrF, E-beam or X-rays.

Thereafter, the photosensitive film is baked, and the exposed portion of the photosensitive film is silylated using hexamethyldisilazane or tetramethyldisilazane as a silylation agent to form a silicide film. The N-Si bond of the silylation agent reacts with R-O-H of the resin to form an R-O-Si bond.

Then, when the photoresist film is developed by a dry development process using an O ₂ plasma, a silicon oxide film is formed on the silicide film, which is resistant to oxygen plasma, and the remaining part is removed to form a photoresist pattern. Then, the photoresist pattern is etched. The exposed etching target layer is etched using a mask to form an etching target layer pattern.

As described above, the present invention includes a chemically-amplified photosensitive film containing imide with high heat resistance on the etched layer when forming a micro pattern using an ArF light source, and capable of resolving even at a small amount of energy, and applying O ₂ plasma. After forming the silicon oxide film by the silylation process, a fine pattern is formed by the dry development method to prevent roughening of the photoresist film generated during the wet development, and to enable resolution at a small amount of energy. Therefore, the use of the photoresist film of the photoresist copolymer according to the present invention enables high integration of semiconductor devices.

Claims (6)

A photoresist copolymer comprising a portion represented by the following formula (2). [Formula 2]

In the above formula, R represents p- (t-butoxycarboxylate) phenyl, 2- (t-butoxycarboxylate) ethyl or 3- (t-butoxycarboxylate) propyl, n is a number of 10-2000 as polymerization degree. A first step of dissolving at least one imide monomer represented by Chemical Formula 1 in a dimethylformamide solvent, A second step of mixing and reacting a polymerization initiator with the resultant of the first step, Method of producing a photoresist copolymer having a third step of forming a photoresist copolymer containing a portion represented by the formula (2) in the result of the second step. [Formula 1]

[Formula 2]

In the above formula, R represents p- (t-butoxycarboxylate) phenyl, 2- (t-butoxycarboxylate) ethyl or 3- (t-butoxycarboxylate) propyl, n is a number of 10-2000 as polymerization degree. The method of claim 2, The second step of the polymerization is a method for producing a photoresist copolymer is performed for 2 to 24 hours at a temperature of 60 to 75 ℃ in a nitrogen or argon atmosphere. A photoresist composition comprising the photoresist copolymer of claim 1, a solvent and a photoacid generator. The method of claim 4, wherein The solvent is a photoresist composition, characterized in that methyl 3-methoxy propionate. The method of claim 4, wherein Said photoacid generator is triphenylsulfonium triflate or dibutylnaphthyl sulfonium triflate.

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