KR101003862B1 - Fine pattern forming method for semiconductor device - Google Patents

Abstract

The present invention relates to a method for forming a fine pattern of a semiconductor device, and to form a multilayer of at least one second photoresist layer comprising a first photoresist layer and a photosensitive polymer having a unit of formula (1), In the process requiring the photoresist layer, the development speed of the upper and lower parts is similar to obtain a uniform and fine pattern.

<Formula 1>

Fine pattern, amine group, photosensitive polymer, photoresist layer

Description

Fine pattern forming method for semiconductor device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a micropattern of a semiconductor device. Specifically, in a process requiring a photoresist layer having a high thickness, it is possible to form a photoresist layer of multiple layers including a photoresist layer containing a basic component. A method for forming a fine pattern of a semiconductor device capable of obtaining a uniform photoresist pattern.

The thickness of the photoresist layer used in the ion implantation process during the semiconductor fabrication process is usually very thick (0.8 μm to 3 μm). This is because the resist of the photoresist against ions is weak, and the remaining film of the photoresist is consumed during the ion implantation process.

Even in the case of using a high thickness photoresist layer as described above due to the recent integration of semiconductor devices, the size of the pattern to be actually formed is very small and a high resolution photoresist should be used. However, the photoresist layer is thick, so the light intensity applied to the upper and lower portions of the photoresist layer during exposure is different, so that even if a photoresist having high resolution is used to form a fine pattern, the photoresist is developed a lot and the lower part is developed. As a result, a trapezoidal positive-slpoe pattern is formed. The thicker the photoresist layer becomes, the deeper this phenomenon becomes, and the purpose of increasing the thickness of the photoresist layer in order to faithfully perform the barrier role of the implant ions is faded.

In order to solve the above problems, an object of the present invention is to provide a method for forming a fine pattern of a semiconductor device capable of forming a uniform and fine pattern in a process requiring a high thickness photoresist layer and a fine pattern.

The present invention to achieve the above object,

It provides a photoresist composition comprising a photosensitive polymer having a repeating unit of the formula (1):

<Formula 1>

The repeating unit may be included in 10 to 40 mol% based on the total repeating units constituting the photosensitive polymer.

The present invention to achieve another object of the present invention,

Forming a first photoresist layer by applying a first photoresist composition to an upper surface of the etched film; And

It provides a method of forming a fine pattern of a semiconductor device comprising applying a photoresist composition comprising the photosensitive polymer on the upper surface of the first photoresist layer to form a second photoresist layer.

The second photoresist layer may be formed of a plurality of layers, and the plurality of layers may be sequentially stacked so that a layer having a high content of the photosensitive polymer is positioned on an upper layer.

The thickness of the second photoresist layer may be 30 to 70% of the thickness of the entire photoresist layer.

According to the method for forming a micropattern of the present invention, even if a photoresist layer having a high thickness is used, a desired profile can be obtained with a vertical and uniform sidewall profile, thereby increasing process efficiency and reducing costs.

When a high thickness photoresist layer is required for ion implantation during a semiconductor manufacturing process, it may be usefully used, and may be applied to a process requiring a fine pattern while using a thick photoresist layer.

Hereinafter, the present invention will be described in detail.

In the present invention, the photosensitive polymer used to form the micropattern of the semiconductor device includes a repeating unit represented by Formula 1 below:

<Formula 1>

The repeating unit may play a role of preventing acid diffusion or consuming acid, including an amine.

The repeating unit of Formula 1 may be included in 10 to 40 mol% based on the total repeating units constituting the photosensitive polymer. When included in less than 10 mol% is difficult to achieve the purpose of the present invention because the effect of the acid diffusion prevention and acid consumption is insignificant, if more than 50 mol% is added to prevent the diffusion and consumption of acid is not formed a pattern You may not.

The photosensitive polymer may be any method known in the art such as radical polymerization, solution polymerization, bulk polymerization or polymerization using a metal catalyst without limitation. Specifically, 3-pyrroline monomers, monomers and polymerization initiators commonly used in the production of photosensitive polymers are dissolved in a polymerization solvent, and then they are dissolved in an inert atmosphere such as nitrogen and argon at a temperature of 30 to 70 ° C. for 4 to 24 hours. Can be prepared by reaction. In addition, the product can be purified using a lower alcohol such as diethyl ether, methanol, ethanol, isopropanol, water or a mixture thereof. The polymerization initiator may be used without limitation to those known in the art, specifically, benzoyl peroxide, 2,2'-azobisisobutyronitrile (AIBN), acetyl peroxide, lauryl peroxide, t-butylper Acetate, t-butylhydroperoxide, di-t-butylperoxide or mixtures thereof can be used. The polymerization solvent can be used without limitation to those known in the art, specifically cyclohexanone, cyclopentanone, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dioxane, methyl ethyl ketone, benzene, toluene, xyl Lene or mixtures thereof may be used.

As a photosensitive polymer having a repeating unit of Formula 1, a photosensitive polymer of Formula 2 may be used:

<Formula 2>

(In Chemical Formula 2,

R ₁ is hydrogen or an alkyl group having 1 to 4 carbon atoms,

R ₂ to R ₄ is an alkyl or cycloalkyl group having 1 to 30 carbon atoms unsubstituted or substituted with hydrogen or fluorine,

a, b, c are mole% with respect to the total repeating units, 1 to 60 mole%,

d is 10 to 40 mol%. )

The photoresist composition of the present invention comprises a photosensitive polymer having a repeating unit of the formula (1). In addition, a photoacid generator and an organic solvent may be further included. Various additives may be further included as needed.

The photosensitive polymer having a repeating unit of Formula 1 may be included in an amount of 1 to 30 parts by weight based on 100 parts by weight of the total photoresist composition. When included in less than 1 part by weight, the photoresist layer is too thin to form a pattern having a desired thickness, and when added in excess of 30 parts by weight, uniformity of the coating may be lowered.

The photoacid generator generates an acid component such as H ⁺ by exposure, and induces a chemical amplification action. Any photoacid generator may be used as a compound capable of generating an acid by light. Sulfur salt compounds, such as onium salt compounds, and mixtures thereof can be used. Non-limiting examples of the photoacid generator are phthalimidotrifluoromethanesulfonate, dinitrobenzyltosylate, n-decyldisulfone, naphthyl naphtha with low absorbance at 157 nm and 193 nm. Naphthylimidotrifluoromethanesulfonate, diphenyltiodonium hexafluorophosphate, diphenyliodonium hexafluoroarsenate, diphenyliodonium hexafluoroantimonate ), Diphenylparatoluenylsulfonium triflate, triphenylsulfonium hexafluoroantimonite, triphenylsulfonium triflate, dibutylnaphthylsulfonium triflate, dibutylnaphthyl trifonate Mixtures thereof and the like.

The photoacid generator may be included in an amount of 0.05 to 20 parts by weight based on 100 parts by weight of the photosensitive polymer. If the amount is less than 0.05 parts by weight, the sensitivity of the photoresist composition to light is reduced, which may make deprotection of the protecting group difficult. If it is added in excess of 20 parts by weight, a large amount of acid may be generated, resulting in poor cross section of the photoresist pattern. have.

In order to form a uniform and flat photoresist layer, the photoresist composition is used by dissolving in the organic solvent having an appropriate evaporation rate and viscosity.

The organic solvent may be used without limitation, those known in the art, specifically, ethylene glycol monomethyl ethyl, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoacetate, diethylene glycol, diethylene glycol Monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol, propylene glycol monoacetate, toluene, xylene, methyl ethyl ketone, methyl isoamyl ketone, cyclohexaone, dioxane, methyl lactate, ethyl lactate, methyl Pyruvate, ethylpyruvate, methylmethoxypropionate, ethylethoxypropionate, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 3-e To oxyethyl propionate, 2-heptaone, gamma-butyrolactone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy 2-methylpropionate, ethoxy acetic acid Methyl, ethyl hydroxy acetate, 2-hydroxy methyl methyl butyrate, 3-methoxy methyl 2-methylpropioate, ethyl 3-ethoxypropionate, ethyl 3-methoxy-2-methylpropionate, ethyl acetate, Butyl acetate and mixtures thereof can be used.

The photoresist composition may further include an organic base as necessary. The organic base may be used without limitation those known in the art, specifically triethylamine, triethylamine, triisobutylamine, triisooctylamine, diethanolamine, triethanolamine and mixtures thereof may be used. have.

The organic base may be included in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the photoresist composition. If it is included in less than 0.01 parts by weight, a t-top phenomenon may occur in the photoresist pattern, and when included in excess of 10 parts by weight, the sensitivity of the photoresist composition may be lowered, resulting in a decrease in pattern formation rate.

The method of forming a fine pattern of a semiconductor device of the present invention comprises the steps of forming a first photoresist layer; And forming a second photoresist layer.

The method for forming a micropattern of the present invention forms a plurality of photoresist layers instead of a single layer and, in the case of the photoresist layer located above, includes a base component to prevent acid diffusion or consume acid. Therefore, a uniform pattern can be obtained even in a process requiring a thick photoresist layer by making the upper and lower developing speeds the same.

The step of forming the first photoresist layer is a step of forming a photoresist layer by applying a first photoresist composition on the top surface of the etched film.

The first photoresist composition may be used without limitation a conventional photoresist composition known in the art, it is preferable to use a photoresist composition containing no photosensitive polymer having a repeating unit of the formula (1) of the present invention. .

The forming of the second photoresist layer is a step of forming a photoresist layer by applying a second photoresist composition including a photosensitive polymer having a repeating unit of Formula 1 on an upper surface of the first photoresist layer.

The repeating unit of Formula 1 includes an amine group to induce H ⁺ toward the amine group, thereby consuming an acid component or preventing diffusion of the acid component, thereby reducing the development speed of the upper layer. Therefore, the developing speed of the upper layer becomes similar to that of the lower layer.

The second photoresist layer may be formed of a plurality of layers. The second photoresist layer may be formed of a plurality of layers by varying the content of the photosensitive polymer in the second photoresist composition according to the pattern of the desired semiconductor device. As the number of layers increases, a more vertical sidewall profile can be obtained, but there is a disadvantage of an increase in processing cost.

When the second photoresist layer is formed of a plurality of layers, the photoresist layer having a higher content of the photosensitive polymer having a repeating unit of Formula 1 may be located at an upper layer. The higher the content of the photosensitive polymer having a repeating unit of Formula 1 is, the greater the effect of preventing acid diffusion, and thus the higher the intensity of light during exposure, so that the higher the upper developing portion, the higher the content of the photosensitive polymer having the repeating unit of Formula 1 This high photoresist layer is placed.

The thickness of the second photoresist layer may be 30 to 70% of the thickness of the entire photoresist layer. If the thickness of the second photoresist layer is less than 30%, the developing speed of the upper part is faster, so that the upper part is more etched, and thus, it is impossible to prevent the formation of a trapezoidal positive-slpoe pattern as in the prior art. Since the photoresist layer itself is too thick, the upper part of the second photoresist layer is etched and the lower part thereof is less so that a jar-shaped pattern may be formed as a whole.

Hereinafter, the present invention will be described in detail through examples. This is for the purpose of illustrating the invention only, and thus the scope of the invention is not limited.

Example 1 Preparation of Photosensitive Polymer

1-1. Dissolve 10 g of AIBN (azobisisobutylronitrile) in 100 g of anhydrous THF with 0.161 mole of 2-methyl-2-adamantyl-5-norbonene-2-carboxylate, 0.161 mole of maleic anhydride, 0.05 mole of 2-methyl-2-adamantyl-methacrylate and as an initiator, The gas was removed using an ampoule as a freezing method, and then polymerized at 66 ° C. for 24 hours. The polymerized reactant was reprecipitated in an excess of diethyl ether to obtain a photosensitive polymer resin.

1-2. 3-pyrroline 0.161 mole, which is a monomer containing an amine, was further included to polymerize in the same manner as in Example 1-1, to obtain a photosensitive polymer resin.

Example 2 Preparation of Photoresist Composition

2-1. 2.0 g of the photosensitive polymer obtained in Example 1-1 and 0.02 g of triphenyl sulfonium triplerate (TPS-105) were completely dissolved in 20 g of propylene glycol monomethyl ether acetate (PGMEA), followed by filtration with a 0.2 μm disk filter. To obtain a first photoresist composition.

2-2. A second photoresist composition was obtained in the same manner as in Example 2-1, except that 2.0 g of the photosensitive polymer obtained in Example 1-2 was used.

Example 3 Photoresist Pattern Formation

3-1. The first photoresist composition prepared in Example 2-1 was applied to the upper surface of the etched film 200 on the semiconductor substrate 100 using a spin coater, followed by baking to form a first photoresist layer having a thickness of 0.2 μm. 310).

3-2. The second photoresist composition prepared in Example 2-2 was coated on the first photoresist layer to form a second photoresist layer 320 in the same manner as in Example 2-1 (FIG. 1A).

3-3. The wafer on which the double layer photoresist layer 300 is formed is prebaked at 100 ° C. for 90 seconds and exposed in a predetermined pattern using an ArF excimer laser having a numerical aperture of 0.6, followed by post exposure baking at 120 ° C. for 90 seconds. ). And it developed for 30 second with 2.38 weight% of TMAH solution, and obtained the photoresist pattern like FIG. 1B.

Comparative Example 1 Photoresist Pattern Formation

1-1. The photoresist composition prepared in Example 2-1 was applied to the top surface of the etched film 200 'of the semiconductor substrate 100' using a spin coater and then baked to form a 0.4 μm photoresist layer 300 '. Was formed (FIG. 2A).

1-2. The wafer on which the photoresist layer was formed was prebaked at 100 ° C. for 90 seconds, exposed to a predetermined pattern using an ArF excimer laser having a numerical aperture of 0.6, and then subjected to post exposure baking (PEB) at 120 ° C. for 90 seconds. And it developed for 30 second with 2.38 weight% of TMAH solution, and obtained the photoresist pattern like FIG. 2b.

Referring to FIG. 1B, in the case of the embodiment in which the double layer photoresist layer is formed, the first photoresist layer formed of the second photoresist layer containing the photosensitive polymer having the monomer of Chemical Formula 1 and the conventional photoresist composition during the development process The developing speeds are similar to form vertical patterns with vertical sidewall profiles.

Referring to FIG. 2B, in the comparative example in which a single layer photoresist layer is formed, the upper portion has a larger exposure amount than the lower portion, and thus the development speed is faster, thereby forming a trapezoidal positive-slope pattern. Therefore, it is difficult to obtain a uniform pattern in a process requiring a thick photoresist layer.

1A is a cross-sectional view of a double layer photoresist layer formed according to an exemplary embodiment of the present invention.

1B is a cross-sectional view of a photoresist pattern formed by a lithography process using a double layer photoresist layer.

2A is a cross-sectional view of a single layer photoresist layer formed by a comparative example of the present invention.

2B is a cross-sectional view of a photoresist pattern formed by a lithography process using a single layer photoresist layer.

Claims (5)

A photoresist composition comprising a photosensitive polymer having a repeating unit of Formula 1 below: <Formula 1>

The method of claim 1, The repeating unit is a photoresist composition, characterized in that contained in 10 to 40 mol% based on the total repeating units constituting the photosensitive polymer. Forming a first photoresist layer by applying a first photoresist composition to an upper surface of the etched film; And And forming a second photoresist layer by applying the photoresist composition of claim 1 to an upper surface of the first photoresist layer. The method of claim 3, The second photoresist layer may be formed of a plurality of layers, and the plurality of layers may be formed in such a manner that the photoresist layer having a high content of the photosensitive polymer of claim 1 is sequentially stacked so as to be positioned in an upper layer. Way. The method of claim 3, And the thickness of the second photoresist layer is 30 to 70% of the total photoresist layer.

Images