KR101059778B1 - Low dielectric norbornene-based copolymer with excellent solubility in organic solvents - Google Patents

Abstract

The present invention is a norbornene-based copolymer comprising at least one monomer selected from the group consisting of norbornene and dicyclopentadiene and a norbornene-based comonomer of the general formula (1), an insulating material for a multi-chip package using the same and An antireflection film of a semiconductor exposure process is provided.

[Formula 1]

In Chemical Formula 1, R ₁ , R _2, and a are as defined in the specification.

The norbornene-based copolymers according to the present invention not only have a low dielectric constant, but also have excellent thermal stability and solubility in organic solvents.

Norbornene-based copolymers, norbornene-based comonomers, thermal stability, solubility

Description

LOW DIELECTRIC NORBORNENE-BASED COPOLYMER HAVING IMPROVED SOLUBILITY TO ORGANIC SOLVENT with Excellent Solubility in Organic Solvents

1 is a ¹ H-NMR spectrum of the norbornene-based comonomer of Example 2 according to the present invention.

2 is a ¹ H-NMR spectrum of the norbornene copolymer of Example 8 according to the present invention.

3 to 5 are graphs showing thermal characteristics of norbornene-based copolymers according to the content of norbornene-based comonomers according to the present invention.

6 is a graph showing the glass transition temperature of the norbornene-based copolymer of Example 21 according to the present invention.

The present invention relates to a norbornene-based copolymer. More specifically, the present invention relates to norbornene-based copolymers having a low dielectric constant and excellent solubility in organic solvents.

Recently, due to the development of information and communication, fast processing speed of massive data is required, and accordingly, it is required to change the chip form of the electronic system from a single chip form into a multichip package in which a plurality of chips are connected in parallel. have. Such a multichip package requires the development of a low dielectric material having excellent physical properties for use in wiring. In particular, the development of filling materials with lower dielectric constants is required to reduce capacitance and signal delay that influence the performance of electronic systems. In addition, low dielectric materials, such as the interlayer dielectric materials of liquid crystal display thin film transistors, are a key material that can lead to weight reduction of products by increasing the speed of devices and reducing energy consumption, beyond the existing simple functions of protecting integrated circuits. Therefore, development of these materials is required.

According to the expectation of the US semiconductor industry, low dielectric materials for multichip packages to be developed before 2005 should have a dielectric constant of 2.0 or less, thermal stability at 300 ° C or higher, and low physical properties. In addition, demand for materials required for the development of high-speed electronic systems through optical wiring as well as electrical wiring is expected after 2005. For this, organic thin film materials should have appropriate refractive index, high light transparency and low light loss.

Conventionally, silicon oxide films (SiO ₂ ) have been used as insulating materials and interlayer insulating materials for semiconductor packages. However, this has a limit as a next-generation chip-to-chip package material because the dielectric constant is as high as 4.0. Accordingly, various attempts have been made to develop low dielectric materials for next generation packages, and the developed low dielectric materials include, for example, polyimide, benzocyclobutene, polynorbornene, and the like.

Among them, polyimide has a high dielectric constant of 2.9 to 3.5, high hygroscopicity, and electrical and optical anisotropy due to polymer structural problems. The benzocyclobutene developed by Dow also has a high dielectric constant of about 2.7, and there is a problem in that the thin film manufacturing process using the same is complicated and the adhesion to metal is poor.

In addition, polynorbornene has excellent physical properties such as excellent thermal stability, low moisture absorption and electrical and optical isotropy, but has a problem of low adhesion to metals. Recently, BF Goodrich Co., Ltd. synthesized polynorbornene by introducing a silicon compound containing an alkoxy group into norbornene to improve the adhesion of polynorbornene to the aforementioned metal. In order to be used as a material for a next generation semiconductor package, it is necessary to develop a material having a lower dielectric constant.

On the other hand, for the process of applying the aforementioned low dielectric material to the product, the low dielectric material should have good solubility in organic solvents. One of the biggest problems of the existing polynorbornene-based copolymers or copolymers is that their solubility in organic solvents is significantly lower. In order to apply a material having low solubility in an organic solvent to a product through a process such as coating, there is a problem such as using a specific solvent above a specific temperature. In order to improve this point, attempts have been made to control the design of the comonomer used in the copolymer, the content of the comonomer in the copolymer, the molecular weight of the copolymer, and the like.

The inventors have found that the use of norbornene-based monomers containing hydroxybenzenes and / or alkoxybenzenes as comonomers in the production of norbornene-based copolymers can improve the solubility of the norbornene-based copolymers in organic solvents. . In particular, it has been found that the use of monomers containing alkoxy benzene as comonomers can also improve the thermal stability of norbornene-based copolymers.

Accordingly, an object of the present invention is to provide a norbornene-based copolymer having excellent solubility in organic solvents and preferably thermal stability.

The present invention provides a norbornene-based copolymer comprising at least one monomer selected from the group consisting of norbornene and dicyclopentadiene and a norbornene-based comonomer of Formula 1 below:

In Formula 1,                     

R ₁ and R ₂ are each selected from the group consisting of a hydroxy group and a straight or branched C _1-12 alkoxy group which is optionally substituted with a phenyl group,

a is an integer of 0-4.

The present invention also provides an insulating material for a multichip package using the norbornene-based copolymer of the present invention and an antireflection film in a semiconductor exposure process.

Hereinafter, the present invention will be described in detail.

As described above, norbornene-based copolymers have high usability, such as heat resistance, low hygroscopicity, electrical and optical isotropy, and optical high transparency, and thus are highly usable as optical wiring materials for next-generation multichip packages and semiconductors. Due to poor solubility, there is a process difficulty. The inventors have found that the use of norbornene-based monomers having hydroxybenzenes and / or alkoxybenzenes as comonomers in the production of norbornene-based copolymers can greatly improve the solubility of the norbornene-based copolymers in organic solvents. . Specifically, it is as follows.

In general, in order to increase the solubility of the polymer, a chain alkyl group is introduced into the comonomer, and the introduced alkyl group gives flexibility to the main backbone of the polymer to increase the solubility in the solvent. However, when the alkyl group is introduced into the polymer as described above, the solubility in the solvent is improved, but the glass transition temperature (Tg) tends to decrease. Similarly, when a norbornene-based copolymer uses a norbornene monomer substituted with an alkyl group as a comonomer, this can improve the solubility in the organic solvent of the norbornene-based copolymer by giving flexibility to the structure of the robust norbornene-based copolymer. However, the norbornene monomer substituted with the alkyl group provides structural flexibility to the norbornene-based copolymer and at the same time, it lowers the glass transition temperature (Tg) of the norbornene-based copolymer and thus thermal stability, which is one of the greatest advantages of the norbornene-based copolymer. Decreases.

However, in the present invention, by using a norbornene monomer having an alkoxybenzene as a comonomer in the production of the norbornene copolymer, not only the solubility in the organic solvent of the norbornene copolymer can be improved, but also the thermal stability of the norbornene copolymer Can also be prevented. Specifically, the comonomer used in the present invention has an alkyl group in alkoxy, but has a benzene ring without fluidity. Accordingly, the alkyl group in the alkoxy of the monomer gives flexibility to the structure of the norbornene-based copolymer to improve the solubility in organic solvents, and at the same time the benzene ring without fluidity prevents the reduction of the glass transition temperature of the norbornene-based copolymer. The thermal stability of the nene copolymer can be maintained. That is, norbornene-based copolymers prepared according to the present invention can greatly improve the solubility in organic solvents, while the thermal properties can maintain a level similar to the pure norbornene polymer.

In the present invention, not only the solubility in various organic solvents of the norbornene-based copolymer can be controlled by using comonomers having various alkoxybenzenes in the preparation of the norbornene-based copolymer, and also the thermal properties of the norbornene-based copolymer The properties of the film can be adjusted.

In the present invention, it is preferable that the comonomer is contained in the norbornene-based copolymer of the present invention in an amount of 0 second and 20 mol% or less. If the comonomer is included in more than 20 mol% of the norbornene-based copolymer, it may affect the physical properties such as mechanical and thermal properties of the norbornene polymer. In addition, since the comonomer is relatively high in price, it is not preferable to include more than the amount of the above range in the copolymer in terms of unit cost. The comonomer may have the same effect as described above even when included in 5 mol% or less of the norbornene-based copolymer of the present invention.

The comonomer of Chemical Formula 1 may be easily prepared by a simple liquid phase reaction rather than a high temperature and high pressure process, which is a process for preparing norbornene-based derivatives. For example, the comonomer of Chemical Formula 1 may be prepared by stirring a benzoquinone series material and a starting material such as cyclopentadiene in an organic solvent and reacting for several hours at room temperature. Starting materials for preparing the comonomer of Formula 1 may be obtained from, for example, a reagent purchased from Aldrich, but is not limited thereto. Synthesis method of the comonomer of the formula (1) is illustrated in detail in the examples to be described later, those skilled in the art can be modified to prepare a variety of comonomers according to the present invention.

The norbornene-based copolymer prepared according to the present invention is a copolymer consisting of norbornene and a comonomer of Formula 1, a copolymer consisting of dicyclopentadiene and a comonomer of Formula 1, and norbornene, dicyclopentadiene and It includes all of the copolymer consisting of the comonomer of the formula (1).

Dicyclopentadiene has a structure in which a pentagonal ring is further attached to norbornene as shown in the following formula. Thus, a copolymer made of norbornene and a comonomer of Formula 1, and a copolymer made of dicyclopentadiene and a comonomer of Formula 1 or a copolymer made of norbornene, dicyclopentadiene and a comonomer of Formula 1 Coalescing is almost similar in framework form, and thus basic properties such as thermal properties and solubility in organic solvents are also similar.

One example of the norbornene-based copolymer of the present invention may have a structure as shown in Formula 2:

In Chemical Formula 2,

R ₁ and R ₂ are each selected from a hydroxy group, and a phenyl group substituted or consisting of a C _1-12 alkoxy, unsubstituted straight or branched chain, the

a is an integer of 0 to 4,

m is an integer from 100 to 200,                     

n is an integer from 200 to 400,

Each of these monomers is randomly located in the copolymer.

The norbornene-based copolymer according to the present invention may be prepared by reacting norbornene and / or dicyclopentadiene with the comonomer of Chemical Formula 1 in a suitable solvent at room temperature. The specific manufacturing method was illustrated in the Example mentioned later.

The norbornene-based copolymer according to the present invention may have excellent solubility in organic solvents such as methylene chloride, tetrahydrofuran, benzene, toluene, chlorobenzene, chloroform and the like by the norbornene-based comonomer having alkoxybenzene contained in the copolymer. In addition, it has a glass transition temperature in the range of 300 to 400 degreeC according to the composition of a copolymer.

The present invention also provides an insulation material for a multichip package manufactured by using the norbornene-based copolymer of the present invention described above and an antireflection film in a semiconductor exposure process.

For example, the copolymer prepared by the above method can be produced into a thin film by spin coating. That is, the copolymer solution of the concentration prepared on the surface-treated Si wafer is immediately dropped while filtering with a filter (for example, 0.2 µm filter), and the rotation speed (rpm) of the spin coater is changed to form a thin film having a desired thickness. The thin film is formed by heat-treating the prepared thin film in air at 90-220 ° C. to evaporate the remaining solvent. At this time, the heat treatment process must be carried out at a temperature below the glass transition temperature of the prepared copolymer, the reason is that when the heat treatment at a temperature above the glass transition temperature of the prepared copolymer the chain of the norbornene-based copolymer fluidity This is because the structure of the formed nano-pores will collapse. The film thus prepared may be used as an insulating material for a multichip package and an antireflection film in a semiconductor exposure process.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

[Production of Comonomer]

Example 1

Synthesis of norbornene comonomer I (1,4-dihydro-1,4-methanonaphthalene-5,8-diol)

16 g of benzoquinone was added while refluxing 10 g of DCPD (dicyclopentadiene) dissolved in 100 mL of methylene chloride (MC) solvent at 150 ° C., and the temperature was lowered to 0 ° C. for 3 hours. 50 mL of ethyl acetate and 20 g of aluminum oxide were added to the product prepared from the reaction, and reduced by ultrasonic irradiation for 1 hour to obtain a pale yellow solid product. Yield: 20 g (80%)

Example 2

Synthesis of norbornene-based comonomer II (5,8-diethoxy-1,4-dihydro-1,4-methanonaphthalene)

10 g of 1,4-dihydro-1,4-methanonaphthalene-5,8-diol synthesized in Example 1 was added to 20 mL of dimethyl sulfoxide solvent. Then, 12.9 g of KOH was added thereto and reacted for 30 minutes, and then 12.5 g of ethane bromide was added and reacted for 30 minutes. After the reaction was completed, 50 mL of water and 50 mL of methylene chloride were added to the reaction solution. 5 g of Na ₂ SO ₄ was added to the extracted methylene chloride solution to remove a small amount of water, and the solvent was evaporated using a pressure reducer to obtain a pale yellow solid. Yield: 13.1 g (99%)

Example 3

Synthesis of norbornene-based comonomer III (5,8-benzyloxy-1,4-dihydro-1,4-methanonaphthalene)

5,8-benzyloxy-1,4-dihydro-1,4-methonanaphthalene was prepared in the same manner as in Example 2 except that 19.6 g of benzyl bromide was used instead of 12.5 g of ethane bromide. Yield: 96%

Example 4

Synthesis of norbornene-based comonomer IV (5,8-octoxy-1,4-dihydro-1,4-methanonaphthalene)

5,8-octoxy-1,4-dihydro-1,4-methanonaphthalene was prepared in the same manner as in Example 2 except that 22 g of octane bromide was used instead of 12.5 g of ethane bromide. Yield: 93%

[Synthesis of norbornene-based copolymer]

Examples 5-10

Into a reactor containing 100 mL of methylene chloride (MC), add allyl palladium chloride dimer as a catalyst and silver hexaflluoroantimonate as an anion and stir well for 30 minutes using a stirrer. It was. Subsequently, 9 g of norbornene and 1 g of norbornene-based comonomer shown in Table 1 were added to the reactor, followed by reaction at room temperature for 12 hours. The reaction was then dropped into methanol / hydrochloric acid (9/1) solution (200 mL) and a solid precipitate formed. After filtering the precipitate, a small amount of solvent remaining in the precipitate was removed in vacuo to obtain a white polymer.

Example Comonomer [Norbornene] / [comonomer] (g / g) [Catalyst] / [monomer] yield 5 Example 1 9/1 1/500 45% 6 Example 2 9/1 1/125 75% 7 Example 2 9/1 1/250 69% 8 Example 2 9/1 1/500 78% 9 Example 3 9/1 1/500 72% 10 Example 4 9/1 1/500 75%

Examples 11-24

In a reactor containing 100 mL of methylene chloride, [Pd (CH ₃ CH ₂ CN) ₄ ] [SbF ₆ ] ₂ was added as a catalyst and thoroughly stirred for 30 minutes using a stirrer. The synthesized norbornene-based comonomer was added in the amounts shown in Table 2 and reacted at room temperature for 12 hours. The reaction was dropped into methanol / hydrochloric acid (9/1) solution (200 mL), at which time a solid precipitate formed. After filtering the precipitate, a small amount of solvent remaining in the precipitate was removed by vacuum to obtain a white polymer.

Example Comonomer [Norbornene] / [comonomer] (g / g) [Catalyst] / [monomer] yield 11 Example 2 9/1 1/125 82% 12 Example 2 9/1 1/250 80% 13 Example 2 9/1 1/500 78% 14 Example 2 9/1 1/1000 77% 15 Example 2 9.5 / 0.5 1/125 70% 16 Example 2 9.5 / 0.5 1/500 72% 17 Example 2 8/2 1/125 56% 18 Example 2 8/2 1/500 63% 19 Example 3 0/10 1/50 7% 20 Example 3 9/1 1/125 76% 21 Example 3 9/1 1/500 72% 22 Example 4 0/10 1/50 4% 23 Example 4 9/1 1/125 56% 24 Example 4 9/1 1/500 45%

[Solubility in Organic Solvents of Norbornene Copolymer]

Comparative Experimental Example 1, Experimental Example 2 to Experimental Example 5

The solubility of the conventional polynorbornene homopolymer (PNB) and the organic solvent of the norbornene-based copolymers of the present invention prepared in Examples 5, 13, 21 and 24 was measured and described in Table 3 below. Indicated. Solubility was expressed by dissolving 0.5 g of polymer per mL of each solvent, O when melting, and X when not melting.

menstruum
(Relative polarity) compare
Experimental Example 1
(PNB) Experimental Example 2
(Example 5) Experimental Example 3
(Example 13) Experimental Example 4
(Example 21) Experimental Example 5
(Example 24) Hexane (1.0) X X X X X Toluene (2.3) X O O O O Diethyl ether (4.3) X X X X X chloroform
(4.8) X O O O O THF (7.6) X O O O O Methylene
Chloride
(MC) (8.9) X O O O O Acetone (21) X X X X X MeOH (32.7) X X X X X DMF (37) X X X X X Dimethyl sulfoxide
(DMSO) (47) X X X X X Chlorobenzene O O O O O

In Table 3, the numerical values in parentheses next to the solvent names are values indicating relative polarities. The higher the value, the greater the polarity.

As shown in Table 3 above, PNB was dissolved only in chlorobenzene in the above solvents, but the copolymer according to the present invention was also dissolved in chloroform, THF and methylene chloride, which are highly polar. In addition, in chlorobenzene, PNB showed a low solubility of 0.1 g / mL, but the copolymers of Examples 5, 13, 21, and 24 showed a solubility of 1 g / mL or more.

[Thermal Stability of Norbornene Copolymer]

The thermal analysis results of the norbornene-based copolymers of the present invention prepared in Examples 6 to 8 are shown in FIG. 3, and the thermal analysis results of the copolymers of Examples 11 to 13 are shown in FIG. 4, and The thermal analysis results of the copolymers of Examples 20, 21, 23, and 24 are shown in FIG. 5. Through these drawings, it can be seen that the thermal stability of the copolymer prepared in the embodiment of the present invention is similar to that of the conventional polynorbornene homopolymer.

On the other hand, Figure 6 is a result of measuring the glass transition temperature of the polynorbornene homopolymer (PNB) and the copolymer prepared in Example 21 (Dynamic Mechanical Analysis). As shown in Figure 6, it can be seen that the glass transition temperature of the copolymer prepared in Example 21 is about 20 ℃ lower than the glass transition temperature of the PNB. It can be seen that the glass transition temperature of the copolymer of Example 21 is not significantly different from the glass transition temperature of the PNB when compared to a norbornene copolymer containing an alkyl group, which is about 100 ° C. lower than the glass transition temperature of the PNB.

[Electro-optical Characterization Test of Thin Films Formed Using Norbornene Copolymer]

After preparing a solution in which the copolymer prepared in the present invention was dissolved to 20 wt% in a mesitylene solvent, spin coating was performed at 2000 rpm for 30 seconds to prepare a thin film. The thickness of the thin film was about 2 μm as measured by the Prism Coupler. Heat treatment to 250 to 450 ℃ to prepare a copolymer thin film.

In order to investigate the electrical properties of the thin film, an aluminum electrode was vacuum deposited on the thin film. Specifically, the aluminum electrode was deposited under a condition of a diameter of 5 mm, a pressure of 10 ⁻⁵ torr or less, and an evaporation rate of 0.5 nm / sec or less to obtain a uniform thickness of about 100 nm.

Investigation of the electrical properties of the copolymer was calculated in the dielectric constant from the maximum capacitance (Capacitance) value of the capacitance-voltage (C-V) curve with a metal-insulator-semiconductor (MIS) structure and are shown in Table 4.

Copolymer Thin film thickness (㎛) Dielectric constant, k Refractive Index (@ 632 nm) Example 8 1.5 2.42 1.508 Example 9 1.43 2.45 1.492 Example 10 0.9 2.55 1.500 Example 11 1.38 2.12 1.27 Example 13 1.39 2.48 1.483 Example 15 1.42 2.28 1.32 Example 18 1.41 2.12 1.27 Example 21 1.01 2.48 1.492 Example 24 0.96 2.48 1.492

As shown in Table 3, the dielectric constant of the norbornene-based copolymer prepared in the above example was lower than 2.6, compared to 2.6 of the conventional polynorbornene homopolymer.

The norbornene-based copolymers of the present invention have excellent solubility in organic solvents by using norbornene-based monomers having hydroxybenzenes and / or alkoxybenzenes as comonomers at the same time, and at the same level as those of conventional polynorbornene homopolymers. It is stable and has a low dielectric constant. Therefore, the norbornene-based copolymer of the present invention can be usefully used as an insulating material for a multi-chip package of the next-generation semiconductor industry and an anti-reflection film material used in a semiconductor exposure process.

Claims (5)

Norbornene-based copolymer comprising at least one monomer selected from the group consisting of norbornene and dicyclopentadiene and a norbornene-based comonomer of the general formula (I): [Formula 1]

In Formula 1, R ₁ and R ₂ are each selected from the group consisting of a hydroxy group and a straight or branched C _1-12 alkoxy group which is optionally substituted with a phenyl group, a is an integer of 0-4. The norbornene-based copolymer of claim 1, wherein the norbornene-based comonomer of Formula 1 is contained in more than 0 20 mol% of the norbornene-based copolymer. The norbornene-based copolymer of claim 1, wherein the norbornene-based copolymer is a copolymer of Formula 2 below: [Formula 2]

In Chemical Formula 2, R ₁ and R ₂ are each selected from the group consisting of a hydroxy group and a straight or branched C _1-12 alkoxy group which is optionally substituted with a phenyl group, a is an integer of 0 to 4, m is an integer from 100 to 200, n is an integer from 200 to 400, Each of these monomers is randomly located in the copolymer. The insulating material for multichip packages using the norbornene-type copolymer of any one of Claims 1-3. The antireflection film of the semiconductor exposure process using the norbornene-type copolymer of any one of Claims 1-3.

Images