JP2896629B2 - Bis (p-tert-butoxyphenyl) sulfoxide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel bis (p-tert-butoxyphenyl) sulfoxide used as an intermediate for synthesizing a sulfonium salt useful as an acid generator for a chemically amplified positive resist composition.

[0002]

2. Description of the Related Art LSI
With the demand for finer pattern rules in line with the higher integration and higher speed of light sources, light exposure, which is currently used as a general-purpose technology, is approaching the intrinsic resolution limit due to the wavelength of the light source. is there. In light exposure using a g-line (436 nm) or an i-line (365 nm) as a light source, a pattern rule of about 0.5 μm is limited, and the integration degree of an LSI manufactured using this is 16 Mbit DR.
AM equivalent. However, LSI prototypes have already been made at this stage, and there is an urgent need to develop further miniaturization techniques.

[0003] Against this background, far-ultraviolet lithography is expected as a next-generation microfabrication technology. This deep ultraviolet lithography is 0.3-0.4μ
m can be processed, and when a resist having low light absorption is used, a pattern having side walls nearly perpendicular to the substrate can be formed. In recent years, attention has been paid to a technique using a high-brightness KrF excimer laser as a light source of far ultraviolet rays, and a resist material having low light absorption and high sensitivity is required to be used as a mass production technique.

A recently developed acid-catalyzed chemically amplified positive resist material (Japanese Patent Publication No. 2-27660,
JP-A-3-27829) is a resist material that has high sensitivity, high resolution, and high dry etching resistance, and has excellent characteristics and is particularly promising for deep ultraviolet lithography.

However, when a conventional chemically amplified positive resist is subjected to deep ultraviolet, electron beam, or X-ray lithography, it is exposed to PEB (Post Exposure).
If the standing time until the Bake is long, the line pattern becomes a T-top shape when the pattern is formed, that is, the pattern upper portion becomes thicker [PED (Po
st Exposure Delay), which is considered to be due to a decrease in the solubility of the resist surface, and is a major drawback in practical use. This makes it difficult to control dimensions in the lithography process,
It also impairs dimensional controllability even when processing a substrate using dry etching [Ref: W.M. Hinsberg,
et al. , J. et al. Photopolym. Sci, T
echnol. , 6 (4), 535-546 (199
3). Kumada, et al. , J. et al. Photo
oppolym. Sci, Technol. , 6 (4),
571-574 (1993)]. There has not yet been a chemically amplified positive resist that solves this problem.

It is believed that the cause of the PED problem in chemically amplified positive resists is largely due to basic compounds in the air. The acid on the resist surface generated by the exposure reacts and deactivates with the basic compound in the air, resulting in PEB
The longer the standing time until, the longer the amount of deactivated acid increases, so that the decomposition of the acid labile group hardly occurs.
Therefore, a hardly-solubilized layer is formed on the surface, and the pattern has a T-top shape.

However, by adding a small amount of a basic compound to the chemically amplified positive resist, the acid concentration distribution at the mask edge can be sharpened even when the optical contrast of the mask pattern is reduced near the resolution limit. It is known that the controllability is improved, and the acid generated by light interference in the mask light-shielding portion is completely neutralized by the basic compound, thereby solving the problem of resist scum (Japanese Patent Laid-Open No. 5-127369). No.).

It is known that the addition of a basic compound can suppress the influence of a basic compound in the air, and thus has an effect also on PED (Japanese Patent Application Laid-Open No. 5-232706; No. 5-249683),
The basic compound used here is not incorporated into the resist film due to volatilization, or has poor compatibility with each component of the resist, and has a problem in reproducibility of the effect because the dispersion is uneven over the width of the resist film. It was found that the resolution was reduced.

Therefore, there is a demand for a chemically amplified positive resist material suitable for microfabrication technology that solves the problem of the surface hardly soluble layer that causes the T-top shape, that is, the problem of PED.

[0010]

Means for Solving the Problems and Actions The present inventor has conducted intensive studies to meet the above-mentioned demand, and as a result, for example, the reaction of thionyl chloride with p-tert-butoxyphenyl Grignard represented by the following formula (2): By doing so, it has been found that a novel bis (p-tert-butoxyphenyl) sulfoxide represented by the following formula (1) can be obtained.

[0011]

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By reacting the sulfoxide of the formula (1) with, for example, trimethylsilyl triflate and a Grignard reagent obtained from metal magnesium and 4-bromo-N, N-dimethylaniline, the sulfonium of the following formula (3) is obtained. A salt is obtained, and this sulfonium salt is suitable as a component of a chemically amplified positive resist material suitable for a microfabrication technique that solves the problem of a surface insoluble layer that causes the T-top shape, that is, the problem of PED, In particular, they have found that they can be very effective in deep ultraviolet lithography. In other words, the sulfonium salt can reduce the effect of the nitrogen-containing substituent, that is, the effect of the deactivation of the acid by the basic compound in the air on the resist surface, so that the surface hardly soluble layer can be formed. The formation is suppressed, and the nitrogen-containing substituent, which is a basic group, is attached to the sulfonium salt, which is an acid generator, so that the compatibility with each component of the resist is good and the dispersion in the resist film is uniform. It has no problem in the reproducibility of the effect, and can enhance the contrast by the effect of the acid labile group, and solves the problem of the surface hardly soluble layer which causes the T-top shape, that is, the problem of the PED. Is effective as a component of a chemically amplified positive resist material suitable for microfabrication technology to be performed. Therefore, the sulfoxide of the above formula (1) is used as an acid generator in such a chemically amplified positive resist material. And finding that it is useful as an intermediate for the formation, in which the present invention has been accomplished.

[0013]

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Now, the present invention will be described in further detail. The present invention provides a bis (p-te) represented by the following formula (1).
rt-butoxyphenyl) sulfoxide.

[0015]

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As described above, bis (p-tert-butoxyphenyl) sulfoxide of the formula (1) is synthesized by reacting p-tert-butoxyphenylgrinier of the formula (2) with thionyl chloride. can do.

[0017]

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In this case, the reaction is preferably carried out in an organic solvent of methylene chloride and THF. When reacting thionyl chloride with a Grignard reagent, thionyl chloride is used in an amount of 1/6 to 1/2 mol, preferably 1 /
The reaction was carried out at a rate of -78 ° C.
The temperature is 70C, preferably -60C to 10C, and the dropping time is 10 to 120 minutes, preferably 45 to 90 minutes. After completion of the reaction, the solvent layer is washed with water, dried and concentrated, and then the target compound can be obtained by recrystallization or column chromatography.

Here, conventionally, in the presence of aluminum chloride,
As a method for synthesizing a sulfoxide using an alkoxybenzene and thionyl chloride, it is known that bis (p-alkoxyphenyl) sulfoxide, for example, bis (p-methoxyphenyl) sulfoxide can be obtained by reacting anisole with thionyl chloride in the presence of aluminum chloride. ing. However, in the synthesis of the desired compound (1) by this method, the desired compound (1) cannot be obtained because the acid generated during the reaction and aluminum chloride, which is a Lewis acid, decompose the tert-butoxy group, which is an acid labile group. .

As a method for synthesizing tert-butyl ether (tert-butoxyphenyl group) with aryl alcohol and isobutene, it is known that aryl alcohol forms tert-butyl ether with isobutene in the presence of an acid catalyst. However, although this method was examined using bis (p-hydroxyphenyl) sulfoxide, the reaction did not proceed due to the low solubility in the reaction solvent such as methylene chloride and THF, and the target compound (1)
[Reference: (1) (a) Nikol]
enko and Krizhechkovskay
a, J. et al. Gen. Chem. USSR, 33 , 3664
(1963), (b) Smiles and Ross
Ignol, J.M. Chem. Soc. , 89 , 696
(1906), (2) Beyerman and Ba
ntekoe, Recl, Trav. Chim. Pa
ys-Bas, 81 , 691 (1962)].

For this reason, as a result of various studies, the present inventor has found that in the synthesis of sulfoxide with alkoxybenzene and thionyl chloride in the presence of aluminum chloride, cleavage of the tert-butoxy group progressed because an acid was generated during the reaction. However, by using a method in which thionyl chloride is added dropwise to the Grignard reagent, the reaction system can always be kept alkaline, the cleavage of the acid labile group is suppressed, and the target compound (1), which has been impossible with the conventional method, can be obtained. It has been successfully obtained by the method described above.

The bis (p-tert-) of the formula (1) of the present invention
Butoxyphenyl) sulfoxide can be used as a synthetic intermediate of a sulfonium salt of the following formula, which is useful as an acid generator of a chemically amplified positive resist composition.

[0023]

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The above sulfonium salt is obtained by adding trimethylsilyl triflate and RM to the sulfoxide of the formula (1).
It can be obtained by reacting a Grignard reagent of gX (R is p-tert-butoxyphenyl, phenyl or dimethylaminophenyl group).

[0025]

According to the present invention, far ultraviolet rays, excimer lasers, electron beams,
In lithography using high-energy rays such as X-rays, highly sensitive sulfonium salts are used as an acid generator, which is one component of a chemically amplified positive resist, and this sulfonium salt is used to remove acids by high-energy rays. Occurs and then causes a catalytic secondary reaction by heating, but by introducing an acid labile group such as a tert-butoxy group into itself, the dissolution rate difference between the high energy beam irradiated part and the non-irradiated part increases. Can be very important for lithography technology. The bis (p-tert-butoxyphenyl) sulfoxide of the present invention is
It is useful as an intermediate of a sulfonium salt having an acid generator as described above, and by using the sulfoxide of the present invention as an intermediate, a sulfonium salt having at least two p-tert-butoxyphenyl groups can be synthesized. it can.

[0026]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Reference Examples, but the present invention is not limited to the following Examples.

[Example] Magnesium 24.3 g (1 mol), p-tert-butoxyphenyl chloride 20
A Grignard reagent prepared by a conventional method using 3.2 g (1.1 mol) and 280 g of THF was diluted with 500 g of THF, and cooled to −60 ° C. or lower in a Doyler ice methanol bath. Then, 47.5 g (0.4 mol) of thionyl chloride was added to T
A solution diluted with 70 g of HF was added dropwise over 1 hour at a temperature not exceeding 0 ° C. After aging for 1 hour in an ice bath, 36 g of water was added to decompose excess Grignard reagent. 400 g of a saturated aqueous solution of ammonium chloride and 300 g of water were further added to 1000 g of methylene chloride to carry out liquid separation, and the organic solvent layer was washed twice with 700 g of pure water. The organic solvent layer was dried over magnesium sulfate, filtered, and the solvent was distilled off under reduced pressure. By recrystallizing the obtained oil, the target compound bis (p-
tert-butoxyphenyl) sulfoxide with a purity of 96
%, 83 g (yield 6) as white crystals having a melting point of 80 to 82 ° C.
0%).

[0028]

Embedded image<¹H-NMR: CDCl_Three, Δ (ppm)> nuclear magnetic resonance
Spectrum 1.34 Ha Singlet 18H 7.01-7.04 Hb Doublet 4H 7.48-7.51 Hc Doublet 4H <IR: (cm^-1)> 2976, 2931, 1589, 1487, 1392,
1367, 1302, 1238, 1159, 1090,
1043, 1009, 930, 893, 852, 827<MS: (m / z)> mass spectrum 346 (M⁺): 331,290 (C₂₀H₂₆O_ThreeS = 34
6) <m. p. : (° C)> melting point 80-82 ° C

Reference Example Trifluoromethanesulfonic acid
Bis (p-tert-butoxyphenyl) (p-dimethyl
Synthesis of bis (p-tert-butoxyphenyl) sulfoxide 8.5 g (0.025 mol), triethylamine 1.3
g (0.013 mol) in methylene chloride (110 g) was dissolved in a dry ice methanol bath at -70.
After cooling to 6.0 ° C., trimethylsilyl triflate 6.0.
g (0.027 mol) was stirred and added dropwise while controlling the temperature so as not to exceed -60 ° C.

Then, the reaction temperature was adjusted to 0 to 5 ° C. by replacing the dry ice methanol bath with an ice water bath, followed by stirring for 10 minutes.

The obtained reaction solution was cooled again to -70 ° C. using a dry ice methanol bath, and 1.2 g (0.049 mol) of magnesium metal, 18.9 g of tetrahydrofuran and 4-bromo-N, A Grignard reagent prepared by a conventional method using 9.9 g (0.049 mol) of N-dimethylaniline was added dropwise while controlling the reaction temperature not to exceed −60 ° C.

Then, the bath was replaced with an ice-water bath again, and the reaction temperature was set to 0 to 0.
The mixture was further stirred for 60 minutes at 5 ° C. to complete the reaction.

After the excess Grignard reagent was decomposed by adding water dropwise to the obtained reaction solution, filtration was performed to remove the generated inorganic salts. The obtained filtrate was washed three times with 130 g of water. The obtained organic layer was dried under reduced pressure to obtain an oily substance. The obtained oil was subjected to silica gel column chromatography to give a yield of 4.8 g (yield 32%) and a purity of 98%.
Of trifluoromethanesulfonic acid bis (p-tert-
(Butoxyphenyl) (p-dimethylaminophenyl) sulfonium was isolated.

The results of nuclear magnetic resonance spectrum (NMR), infrared spectrum (IR), and elemental analysis of the obtained bis (p-tert-butoxyphenyl) (p-dimethylaminophenyl) sulfonium trifluoromethanesulfonate are shown below. Shown below. < ¹ H NMR: CDCl ₃ , δ (ppm)>

[0035]

Embedded image Next, 80 parts by weight of polyhydroxystyrene partially protected by an OH group represented by the following formula (Polym. 1) with a t-butoxycarbonyl group, and bis (p-tert-butoxyphenyl) trifluoromethanesulfonate ( p
-Dimethylaminophenyl) sulfonium (3 parts by weight) represented by the following formula (DRI.1):
20 parts by weight of a tert-butoxycarbonyloxyphenyl) propane dissolution inhibitor were dissolved in 450 parts by weight of 1-ethoxy-2-propanol to prepare a resist solution.

This was filtered through a 0.2 μm Teflon filter to prepare a resist solution. This is spin-coated on a silicone wafer and
m. Then, this silicone wafer was
Baking was performed on a hot plate at 0 ° C. for 120 seconds.

Then, exposure was performed using an excimer laser stepper (Nikon Corporation, NSR 2005EX NA = 0.5), baking was performed at 90 ° C. for 60 seconds, and development was performed using a 2.38% aqueous solution of tetramethylammonium hydroxide. As a result, a positive pattern was obtained.

[0038]

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The obtained resist pattern was evaluated as follows. First, the sensitivity (Eth value) was determined. Next, 0.
4 μm line and space top and bottom:
The exposure amount resolved at 1 was taken as the optimum exposure amount, and the minimum line width of the separated lines and spaces at this exposure amount was taken as the resolution of the evaluation resist. The shape of the resolved resist pattern was observed using a scanning electron microscope. The stability of the PED of the resist is as follows: after exposure at the optimal exposure amount, the baking time is changed by changing the leaving time, and the time when the change in the resist pattern shape is observed, for example, the line pattern becomes a T-top shape or can be resolved. It was evaluated at the time when it disappeared. That is, the longer this time, the better the PED stability.

As a result, the sensitivity was 115.0 mJ / c.
m ² , resolution 0.28 μm, pattern shape is good,
The PED stability was over 120 minutes.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Watanabe 28-1 Nishifukushima, Nishi-Jukumura, Nakakubijo-gun, Niigata Shin-Etsu Chemical Co., Ltd. Synthetic Technology Research Institute (72) Inventor Yoshifumi Takeda Nishigata-ku, Niigata 28-1 Nishifukushima Shin-Etsu Chemical Co., Ltd. Synthetic Technology Laboratory (56) References US Patent 4451409 (US, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) CA (STN) REGISTRY ( STN)

Claims (1)

(57) [Claims] 1. A bis (pt) represented by the following formula (1):
tert-butoxyphenyl) sulfoxide. Embedded image