KR101061526B1 - Resist for Electron Beam Lithography - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to resists for electron beam lithography, and more particularly to negative resists copolymerized with two types of organosiloxane compounds. By using the resist for electron beam lithography of the present invention, not only the sensitivity to the electron beam is high, but also the manufacturing is easy and the resist property is more uniform even if stored for a long time, thereby producing a semiconductor device of superior quality.

Lithography, Negative, Resist, Alkoxysilane, Copolymerization

Description

Resist for e-beam lithography

TECHNICAL FIELD The present invention relates to a resist for electron beam lithography, and more particularly, a resist for electron beam lithography, which is not only highly sensitive to an electron beam but also easy to manufacture and has a more uniform resist characteristic even after long-term storage, thereby enabling fabrication of a semiconductor device of higher quality. It is about.

As the semiconductor manufacturing process becomes complicated and the degree of integration of semiconductor devices increases, the formation of fine patterns is required.

Currently, the most widely used negative electron beam resist is hydrogen silsesquioxane (HSQ), and it is known that HSQ can form a pattern of 30 nm or less superior to other chemically amplified negative resists. However, HSQ is known to form a ring-shaped structure based on the Si-O-Si main chain, and is a structure in which hydrogen is bonded to a silicon atom, and all are made of inorganic materials.

Since the size of the hydrogen atoms bonded to the silicon atoms is very small, the sol-gel synthesis method that is commonly used is difficult to synthesize due to the short gelation time, and is unstable enough to change the molecular weight with storage time. There was a disadvantage that this was not constant. In addition, there is a disadvantage in that the sensitivity required for the electron beam is lower than the organic electron beam resist, so the exposure amount required for pattern formation is large.

Therefore, there is room for improving the disadvantage of HSQ as a negative electron beam resist.

The problem to be solved by the present invention is to provide a resist for electron beam lithography that is not only excellent in sensitivity and resolution to the electron beam, but also easy to manufacture and has a uniform resist characteristic even after long-term storage.

One aspect of the electron beam lithography resist according to the present invention for solving the above technical problem is that the compound of Formula 1 and the compound of Formula 2 is copolymerized to form a copolymer, the number average molecular weight of the copolymer is 500 To 30,000.

<Formula 1>

<Formula 2>

In Formula 1 and Formula 2, R ¹ to R ⁹ are hydrogen or an alkyl group having 1 to 5 carbon atoms, X in Formula 1 is hydrogen, a hydroxy group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and novo It is any one of a nil group, a C8-C13 norbornylalkyl group, a norbornenyl group, a C8-C13 norbornenylalkyl group, a C7-C12 haloalkylphenyl group, and a C8-C18 haloalkylphenylalkyl group, and Z in 2 is an alkyl group having 1 to 6 carbon atoms or any one of the following formulas 3 to 5,

<Formula 3>

<Formula 4>

<Formula 5>

In Formula 5, R ¹⁰ is an alkyl group having 2 to 6 carbon atoms.

Another aspect of the resist for electron beam lithography according to the present invention for solving the above technical problem is that the compound of formula 9 and the compound of formula 10 is copolymerized to form a copolymer, the number average molecular weight of the copolymer is 500 To 30,000.

<Formula 9>

<Formula 10>

In Formulas 9 and 10, R ¹¹ to R ¹⁶ are hydrogen or an alkyl group having 1 to 5 carbon atoms, and in Formula 9, A is a norbornyl group, a carbonyl group having 8 to 13 carbon atoms, a norbornenyl group and a carbon group having 8 to 13 carbon atoms. It is any one of the norbornenylalkyl group, D in Formula 10 is hydrogen, a hydroxy group, an alkyl group of 1 to 5 carbon atoms, an alkoxy group of 1 to 5 carbon atoms, a haloalkylphenyl group of 7 to 12 carbon atoms and haloalkyl of 8 to 18 carbon atoms It is either phenylalkyl group.

By using the resist for electron beam lithography of the present invention, not only the sensitivity and resolution of the electron beam are high, but also the manufacturing is easy and the resist characteristics are more uniform even if stored for a long time, thereby producing a semiconductor device of higher quality.

The present invention provides a resist for electron beam lithography in which a compound of formula 1 and a compound of formula 2 are copolymerized to form a copolymer, and the copolymer has a number average molecular weight of 500 to 30,000.

<Formula 1>

<Formula 2>

In Formula 1 and Formula 2, R ¹ to R ⁹ are hydrogen or an alkyl group having 1 to 5 carbon atoms. In Formula 1, X is hydrogen, a hydroxy group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a norbornyl group, a norbornylalkyl group having 8 to 13 carbon atoms, a norbornenyl group, a norbornenylalkyl group having 8 to 13 carbon atoms, It is either a haloalkylphenyl group having 7 to 12 carbon atoms and a haloalkylphenylalkyl group having 8 to 18 carbon atoms. Z in Formula 2 is an alkyl group having 1 to 6 carbon atoms or any one of the following Formulas 3 to 5.

<Formula 3>

<Formula 4>

<Formula 5>

R ¹⁰ in Formula 5 is an alkyl group having 2 to 6 carbon atoms.

The present invention also provides a resist for electron beam lithography in which a compound of formula 9 and a compound of formula 10 are copolymerized to form a copolymer, and the copolymer has a number average molecular weight of 500 to 30,000.

<Formula 9>

<Formula 10>

In Formulas 9 and 10, R ¹¹ to R ¹⁶ are hydrogen or an alkyl group having 1 to 5 carbon atoms. In formula (9), A is any one of a norbornyl group, a norbornelalkyl group having 8 to 13 carbon atoms, a norbornenyl group and a norbornenylalkyl group having 8 to 13 carbon atoms. D in Formula 10 is any one of hydrogen, a hydroxy group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a haloalkylphenyl group having 7 to 12 carbon atoms, and a haloalkylphenylalkyl group having 8 to 18 carbon atoms.

In the case of copolymerizing the compound of Formula 1 and the compound of Formula 2 or when copolymerizing the compound of Formula 9 and the compound of Formula 10, the size of the organic functional group bonded to the silicon atom is large, so that the reaction rate is controlled during sol-gel synthesis. In addition to being relatively easy to follow, the resist for electron beam lithography of the present invention, the produced product, also shows excellent stability.

The resist for electron beam lithography according to the present invention has a number average molecular weight of about 500 to about 30,000 as described above. Since the number average molecular weight can be easily measured using a gel permeation chromatography method or the like which is well known in the art, the measurement method will not be described in detail.

The number average molecular weight is preferably in the range of 1000 to 5000. If the number average molecular weight is less than 1000, the sensitivity becomes worse. Is disadvantageous.

However, in the molecular weight distribution, the resist for electron beam lithography of the present invention has a polydispersity index of nearly 1, so that the weight average molecular weight is almost the same as the range of the number average molecular weight. Preferably, the polydispersity may be 1 to 1.3.

When polymerizing the compound of Formula 1 and the compound of Formula 2, the ratio of the repeating unit derived from the compound of Formula 1 and the repeating unit derived from the compound of Formula 2 may be slightly different from the ratio added as a reactant. This is influenced by the reaction characteristics of each functional group and the affinity with water. For example, in the case of a copolymer containing a large number of relatively hydrophobic monomers containing functional groups such as phenyl group or norbornenyl group, the hydrophobic monomer may participate in the reaction relatively little and the fraction of the repeating unit may be relatively low. The same applies to the polymerization of the compound of Formula 9 with the compound of Formula 10.

In particular, in the copolymerization of the compound of Formula 1 with the compound of Formula 2 to form a resist for electron beam lithography, the compound of Formula 1 may be one or more selected from the group consisting of the following formulas (6) to (8). In Formulas 6 to 8, R ¹ to R ³ have the same definitions as in Formula 1 described above.

<Formula 6>

<Formula 7>

<Formula 8>

In formula (8), M is a halogen group element.

In copolymerizing the compound of Formula 9 with the compound of Formula 10 to form a resist for electron beam lithography, the compound of Formula 9 is a compound of Formula 11, and the compound of Formula 10 is selected from the group consisting of compounds of Formula 12 and Formula 13 It may be more than one. In Formula 11, R ¹¹ to R ¹³ have the same definitions as in Formula 9 described above. And in Formulas 12 and 13, R ¹⁴ to R ¹⁶ have the same definitions as in Formula 10 described above.

<Formula 11>

<Formula 12>

<Formula 13>

In Formula 13, Q is a halogen group element.

In forming the resist for electron beam lithography by copolymerizing the compound of Formula 9 with the compound of Formula 10, the molar ratio of the repeating unit of the compound of Formula 9 to the repeating unit of the compound included in the copolymer is preferably 20 to 40%. Do. If the molar ratio of the repeating unit of the compound of Formula 9 is less than 20%, a problem of deterioration of resolution may occur. In addition, when the molar ratio of the repeating unit of the compound of Formula 9 is greater than 40%, a problem occurs that the roughness of the edge portion of the pattern formed because the resist for electron beam lithography is poorly developed.

In particular, a hydroxyl group may be formed at an end of the resist for electron beam lithography according to the present invention, and a molar ratio of the hydroxyl group to a functional group formed on the entire terminal of the resist for electron beam lithography may be 50% or less.

The chemical mechanism of crosslinking in response to an electron beam to be irradiated after the resist for electron beam lithography of the present invention is applied on a semiconductor substrate is not yet clear. However, there is a silanol (-Si-OH) group at the end of the polymer constituting the resist, it is assumed that they are activated by the electron beam to cause a crosslinking reaction. In addition, in the case of a polymer containing a haloalkylphenyl group, it is assumed that halogen atoms are released by electron beams, and radicals are formed in alkyl groups, thereby crosslinking by polymerization of alkyl radicals. In the case of the norbornenyl group, it is assumed that the double bonds of the norbornenyl group are broken and crosslinked by adjoining neighboring norborneneyl groups or other alkyl radicals.

In order to prepare a copolymer using the compound of Formula 1 and the compound of Formula 2, the compound of Formula 1 and the compound of Formula 2 may be added to a reactor together with a solvent and stirred with an acid or a base as a catalyst.

The solvent is alcohol (methanol, ethanol, isopropyl alcohol, n-propyl alcohol, butyl alcohol), dimethylacetamide (DMAc), dimethylformamide, dimethyl sulfoxide (DMSO), N-methylpyrrolidone, tetrahydrofuran Organic solvents such as (THF) and water may be used but are not limited thereto.

The weight ratio of the reactant (compound 1 and compound 2) to the solvent is not particularly limited, but for example, the concentration of the reactant may be selected in the range of 20 to 80%.

As the acid / base catalyst, all of the acid / base catalysts used in the general sol-gel reaction can be used. More specifically, the acid catalysts include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as p-toluene-sulfonic acid. Tetramethylammonium hydroxide (TMAH), tetrabutylammonium hydroxide (TBuAOH), NaOH, sodium carbonate, triethylamine, di-n-propylamine, and the like may be used as the base catalyst. However, not limited to this, other acid / base catalysts may also be used. The content of the acid / base catalyst may be 0.005 to 0.3 mol based on 1 mol of the total reactant.

The preferred temperature of the copolymerization reaction may be selected at a properly elevated temperature, but for example, it may be carried out at a temperature of 40 ℃ to 90 ℃, it is preferably carried out in the range of 50 ℃ to 70 ℃. And the preferred reaction time of the copolymerization reaction may be about 4 hours to about 16 hours, it is preferably carried out for 8 hours to 12 hours.

The product of the copolymerization reaction can be separated, for example, through phase separation and drying.

The method of preparing the copolymer using the compound of Formula 9 and the compound of Formula 10 is similar to the method of preparing the copolymer using the compound of Formula 1 and the compound of Formula 2 described above.

Hereinafter, the structure and effects of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention and are not intended to limit the scope of the present invention.

Preparation of Copolymer

&Lt; Example 1 >

To prepare a copolymer, pCMPTMS (p-chloromethylphenyltrimethoxy silane) represented by Formula 14 was used as a compound of Formula 1, and copolymerized using BTESE (bis (triethoxysilyl) ethane) represented by Formula 15 as a compound of Formula 2. .

<Formula 14>

&Lt; Formula 15 >

First, after supplying nitrogen to the reactor in which the reflux unit is installed, the internal pressure is adjusted to 1 atm, and then pCMPTMS and BTESE as monomers are added to the reactor so that the molar ratio is 50:50, and tetrahydrofuran is reacted as a solvent (pCMPTMS and BTESE). ) Concentration was 40 wt%. Thereafter, hydrochloric acid to be used as a catalyst was quantified so that the molar ratio of the monomer was 0.03, and the molar ratio of water and the reactants (pCMPTMS and BTESE) was fixed at 10 and reacted at 60 ° C. for 6 hours.

After the reaction was completed, the catalyst was removed through phase separation using an ether / water layer, and water in the remaining ether layer was removed with magnesium sulfate (MgSO ₄ ). And ether was removed with a rotary vacuum evaporator to obtain a product.

The number average molecular weight of the product was measured by gel permeation chromatography (manufactured by Waters). Polystyrene standard was used as a standard. As a result, the number average molecular weight was measured to be 1200.

<Example 2>

The reaction product was obtained in the same manner as in Example 1 except that potassium hydroxide (KOH) was used at the same concentration instead of hydrochloric acid as a catalyst. In addition, the number average molecular weight was measured to be 3000 as a result of measuring the number average molecular weight in the same manner.

<Example 3>

The reaction product was obtained in the same manner as in Example 1, except that pCMPTMS and BTESE were used as monomers in a molar ratio of 90:10. In addition, the number average molecular weight was measured to be 1100 as a result of measuring the number average molecular weight in the same manner.

<Example 4>

To prepare a copolymer, BHET ([(bicycloheptenyl) ethyl] triethoxy silane) represented by Formula 16 was used as a compound of Formula 1, and copolymerized using BTESE represented by Formula 15 as a compound of Formula 2.

<Formula 16>

First, after supplying nitrogen to the reactor in which the reflux unit is installed, the internal pressure is adjusted to 1 atm, and then BHET and BTESE as monomers are added to the reactor so that the molar ratio is 70:30, and tetrahydrofuran as a solvent is reacted (BHET and BTESE). ) Was added at a concentration of 30 wt%. Thereafter, hydrochloric acid to be used as a catalyst was quantified so that the molar ratio of the monomer was 0.03, and the molar ratio of water and the reactants (BHET and BTESE) was fixed at 3 and reacted at 60 ° C. for 6 hours. After the reaction was completed, the product was obtained in the same manner as in Example 1. As a result of measuring the number average molecular weight in the same manner as in Example 1, the number average molecular weight was determined to be 1450.

&Lt; Example 5 >

The reaction product was obtained in the same manner as in Example 4 except that BHET and BTESE were molar ratios 60:40 as monomers. In addition, the number average molecular weight was measured to be 1600 as a result of measuring the number average molecular weight in the same manner.

<Example 6>

The reaction product was obtained in the same manner as in Example 4, except that BHET and BTESE were used as monomers in a molar ratio of 40:60. In addition, the number average molecular weight was measured to be 1750 as a result of measuring the number average molecular weight in the same manner.

Example 7

To prepare the copolymer, BHET shown in Formula 16 was used as the compound of Formula 9 and copolymerized using pCMPTMS shown in Formula 14 as the compound of Formula 10.

First, after supplying nitrogen to the reactor in which the reflux unit is installed, the internal pressure is adjusted to 1 atm, and then BHET and pCMPTMS as monomers are added to the reactor so that the molar ratio is 20:80, and tetrahydrofuran as a solvent is reacted (BHET and pCMPTMS). ) Was added at a concentration of 30 wt%. Thereafter, hydrochloric acid to be used as a catalyst was quantified so that the molar ratio of the monomer was 0.03, and the molar ratio of water and the reactants (BHET and pCMPTMS) was fixed at 3 and reacted at 60 ° C. for 6 hours. After the reaction was completed, the product was obtained in the same manner as in Example 1. As a result of measuring the number average molecular weight in the same manner as in Example 1, the number average molecular weight was determined to be 1500.

Example 8

To prepare a copolymer, BHET represented by Formula 16 was used as a compound of Formula 9, and copolymerized using triethoxy silane represented by Formula 17 as a compound of Formula 10.

<Formula 17>

First, after supplying nitrogen to the reactor in which the reflux unit is installed, the internal pressure is adjusted to 1 atmosphere, and then BHET and triethoxy silane as monomers are added to the reactor so that the molar ratio is 30:70, and tetrahydrofuran as a solvent is reacted ( BHET and triethoxy silane) concentrations were added to 30 wt%. Thereafter, hydrochloric acid to be used as a catalyst was quantified so that the molar ratio of the monomer was 0.03, and the molar ratio of water and the reactants (BHET and triethoxy silane) was fixed at 3 and reacted at 60 ° C. for 6 hours. After the reaction was completed, the product was obtained in the same manner as in Example 1. As a result of measuring the number average molecular weight in the same manner as in Example 1, the number average molecular weight was measured to be 1300.

Comparative Example

A commercial HSQ (hydrogen silsesquioxane) product manufactured by Dow Chemical Company was used.

Resist Characteristic Evaluation

After dissolving the synthesized copolymer or polymer in a methyl isobutyl ketone solvent, respectively, a transparent thin film was obtained through spin coating. In particular, HSQ (manufactured by Dow Chemical Co., Ltd.) was used as a comparative example.

The baking process is not performed, and a square pattern of 50 μm each, vertically and vertically, is coated on the coated thin film using an electric current of 800 pA using an electron beam lithography apparatus having an acceleration voltage of 19 keV, in the range of 5 to 900 μC / cm ² . After adjusting at 35, and the thickness of the remaining thin film through the development process was measured to obtain the results as shown in the graph of FIG. A 25 wt% aqueous solution of tetramethylammonium hydroxide (TMAH) was used as a developer. The portion not exposed to the electron beam dissolved and disappeared in the developer, and exhibited a negative type resist property in which the exposed portion remained.

As shown in the graph of Figure 1, compared with HSQ (Comparative Example), the resist of Example 3 showed a sensitivity improvement of about 10%, and the resist of Example 1 showed a sensitivity improvement of 35% or more. It was. In the case of the resist of Example 2, a sensitivity improvement of 50% or more was shown. In particular, it can be seen that Examples 4, 5, 6 and 8 show a very significant sensitivity improvement compared to HSQ (Comparative Example).

Line-and-Space Formation Experiment

In order to test the performance of the electron beam lithography resist of the present invention, spin coating the electron beam lithography resist of Example 3 on a silicon substrate and the line widths were 100 nm, 80 nm, 60 nm, 50 nm, 40 nm, and 30 nm, respectively. We tested whether the line-and-space is well formed. Experiments were performed using an exposure dose of 400 μC / cm ² using a current of 170 pA to 180 pA. The results are shown in FIG. Then, the resists of Examples 7 and 8 were spin-coated on the silicon substrate, and the line width was set to 30 nm to test whether the line-and-space was well formed. The results taken with the electron microscope are shown in FIGS. 3 (a) and 3 (b), respectively.

As shown in FIG. 2, the line-and-space was well formed even with a line width of 100 nm, as well as with a line width of 30 nm. 3 (a) and 3 (b) also observed that the line-and-space was well formed even at the 30nm line width.

It can be seen that when forming a pattern of 50 nm or less with the conventional HSQ, a dose of approximately 900 μC / cm ² is required with a 20 keV electron beam, so that an equivalent pattern can be formed even with a significantly lower dose. . In particular, in the case of Examples 7 and 8 it can be seen that it has a much better resolution even with a significantly smaller charge exposure compared to HSQ, it is possible to easily form a pattern of 30nm or less.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, The present invention may be modified in various ways. Therefore, modifications of the embodiments of the present invention will not depart from the scope of the present invention.

As described above, the present invention is useful in a semiconductor manufacturing process for producing a semiconductor device of high density.

1 is a graph showing the results of a resist characteristic evaluation performed using the resists of Examples 1 to 8 and Comparative Examples of the present invention.

2 is an electron micrograph of a line-and-space pattern formed using the resist of Example 2 of the present invention.

3 (a) is an electron micrograph of a line-and-space pattern formed using the resist of Example 7 of the present invention, and FIG. 3 (b) is a line formed by using the resist of Example 8 of the present invention. An electron micrograph of a -n-space pattern.

Claims (11)

Resin for electron beam lithography, characterized in that the compound of formula 1 and the compound of formula 2 is copolymerized to form a copolymer, the number average molecular weight of the copolymer is 500 to 30,000. <Formula 1>

<Formula 2>

In Formula 1 and Formula 2, R ¹ to R ⁹ are hydrogen or an alkyl group having 1 to 5 carbon atoms, X in Formula 1 is hydrogen, a hydroxy group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and novo It is any one of a nil group, a C8-C13 norbornylalkyl group, a norbornenyl group, a C8-C13 norbornenylalkyl group, a C7-C12 haloalkylphenyl group, and a C8-C18 haloalkylphenylalkyl group, and Z in 2 is an alkyl group having 1 to 6 carbon atoms or any one of the following formulas 3 to 5, <Formula 3>

<Formula 4>

<Formula 5>

In Formula 5, R ¹⁰ is an alkyl group having 2 to 6 carbon atoms. The method of claim 1, Wherein the compound of formula 1 is at least one selected from the group consisting of the compound of formula 6 to formula 8 resist for electron beam lithography: <Formula 6>

<Formula 7>

<Formula 8>

In Formulas 6 to 8, R ¹ to R ³ are hydrogen or an alkyl group having 1 to 5 carbon atoms, and M in Formula 8 is a halogen group element. The method of claim 1, Resin for electron beam lithography, characterized in that the molar ratio of the hydroxyl group to the functional group bonded to the silane group end of the copolymer is 50% or less. The method of claim 1, A resist for electron beam lithography, characterized in that the number average molecular weight of the copolymer is 1000 to 5000. The method of claim 1, Resin for electron beam lithography, characterized in that the polydispersity index of the copolymer is 1 to 1.3. Resin for electron beam lithography, characterized in that the compound of formula 9 and the compound of formula 10 is copolymerized to form a copolymer, the number average molecular weight of the copolymer is 500 to 30,000. <Formula 9>

<Formula 10>

In Formulas 9 and 10, R ¹¹ to R ¹⁶ are hydrogen or an alkyl group having 1 to 5 carbon atoms, and in Formula 9, A is a norbornyl group, a carbonyl group having 8 to 13 carbon atoms, a norbornenyl group and a carbon group having 8 to 13 carbon atoms. It is any one of the norbornenylalkyl group, D in Formula 10 is hydrogen, a hydroxy group, an alkyl group of 1 to 5 carbon atoms, an alkoxy group of 1 to 5 carbon atoms, a haloalkylphenyl group of 7 to 12 carbon atoms and haloalkyl of 8 to 18 carbon atoms It is either phenylalkyl group. The method of claim 6, The compound of Formula 9 is a compound of Formula 11, Wherein the compound of formula 10 is at least one selected from the group consisting of compounds of formula 12 and formula 13 for electron beam lithography resist: <Formula 11>

<Formula 12>

<Formula 13>

R ¹¹ to R ¹³ in Formula 11 are hydrogen or an alkyl group having 1 to 5 carbon atoms, R ¹⁴ to R ¹⁶ in Formula 12 and 13 are hydrogen or an alkyl group having 1 to 5 carbon atoms, and Q in Formula 13 is a halogen group element to be. The method of claim 6, The molar ratio of the repeating unit of the compound of formula 9 to the repeating unit of the compound contained in the copolymer is 20 to 40%, characterized in that the resist for electron beam lithography. The method of claim 6, Resin for electron beam lithography, characterized in that the molar ratio of the hydroxyl group to the functional group bonded to the silane group end of the copolymer is 50% or less. The method of claim 6, A resist for electron beam lithography, characterized in that the number average molecular weight of the copolymer is 1000 to 5000. The method of claim 6, Resin for electron beam lithography, characterized in that the polydispersity index of the copolymer is 1 to 1.3.

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