JPS60212404A - Perfluoroalkyl group-containing polymer - Google Patents

Abstract

PURPOSE:A novel polymer useful as a resist material having high sensitivity and high resolving power, showing radiation sensitivity, containing a specific perfluoroalkyl group. CONSTITUTION:For example, a perfluoroalkylaryl iodonium shown by the formula I [Rf is 2-20C perfluoroalkyl; Ar is (substituted)phenyl; R is 1-5C perfluoroalkyl, lower alkyl, or OH] is reacted with a polymer (e.g., poly alpha-methylstyrene, etc.) consisting of a repeating unit shown by the formula II (R<1> is 1-5C alkyl), to give a novel polymer containing a perfluoroalkyl group shown by the formula III[x and y show numbers of each monomer unit, value of x/(x+y) is 0.01- 1.0].

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel perfluoroalkyl group-containing polymer that exhibits radiation sensitivity and is useful as a resist material having high sensitivity and high resolution. More specifically, it relates to a perfluoroalkyl group-containing polymer represented by the general formula (wherein Rf represents a perfluoroalkyl group having 2 to 20 carbon atoms; R1 represents an alkyl group having 1 to 5 carbon atoms; ! and ! each represent the number of each monomer unit in the polymer, and the value of X+1 is in the range from α01 to 1.0).

The perfluoroalkyl group-containing polymer represented by the general formula (1) can be used in various ways by taking advantage of the properties of the perfluoroalkyl group. For example, it can be used as a resist material for radiation such as electron beams or X-rays used during microfabrication in the manufacture of semiconductor integrated circuits.

In recent years, with the increasing density and integration of semiconductor integrated circuits, resist materials sensitive to electron beams or X-rays have been strongly sought after as practical resist materials. Against this background, the present inventors completed the present invention through intensive research based on unique molecular design.

That is, the perfluoroalkyl group-containing polymer represented by general formula (1) is a completely new product synthesized for the first time by the present inventors.

The method for producing the polymer of the present invention is a perfluoroalkylaryl iodonium salt represented by the general formula (wherein, Rf is a perfluoroalkyl group having 2 to 20 carbon atoms, Ar is a substituted or unsubstituted phenyl group, R represents a perfluoroalkyl group, lower alkyl group, or hydroxyl group having 1 to 5 carbon atoms) and a repeating unit represented by the general formula (in the formula, R1 represents an alkyl group having 1 to 5 carbon atoms). ).

Below, the polymer of the present invention and its manufacturing method will be described in more detail.

The weight average molecular weight of the polymer of the present invention is not particularly limited, but if it is several thousand or more, there is no problem in using the polymer of the present invention. Further, the molecular weight distribution of the polymer of the present invention is not particularly limited, and the value expressed by weight average molecular weight/number average molecular weight ranges from a narrow range of 1.0 to 1.1 to a narrow range of 20 to 50. Everything even broader is within the scope of the present invention.

In general formula (1), the value represented by 7etT (hereinafter referred to as perfluoroalkyl group ratio) needs to be 001 or more in order to exhibit the characteristics of the perfluoroalkyl group.

Furthermore, the polymer of the present invention comprises a monomer unit represented by the general formula (wherein R1 and Rf are the same as those described in the general formula (II) and @)) and a monomer unit represented by the general formula (II [ The scope of the present invention includes all monomer units represented by l arranged in blocks, alternately arranged, or randomly arranged.

Examples of the above-mentioned polymers of the present invention include the following.

1so-03F? As mentioned above, the polymer of n-U4 filtration failure (■) can be produced by reacting a compound represented by the general formula (H) with a polymer consisting of a bonding unit represented by the general formula (n). However, the type and amount of the compound represented by general formula (U) used as a raw material for production should be selected depending on the perfluoroalkyl group to be introduced and its B11 (perfluoroalkylation rate), and The synthesis of the compound itself is described in J. Fluorine Ohem, 20 (1982
)695.

Examples of the compound represented by the general formula (11) include the following. The polymer composed of repeating units represented by the general formula (I The molecule h (and the molecular weight distribution remain unchanged in the product except for changes due to the introduction of perfluoroalkyl groups. Therefore,
The raw material polymer has the molecular structure and single-weight average molecular structure desired for the product polymer of the present invention, for example, several thousand or more,
and molecular weight distribution, e.g. weighted average molecule! Polymers must be selected that have a number average molecular weight of 16 ranging from a narrow range of 1.0 to 1.1 to a wide range of 20 to 50.

Examples of polymers consisting of repeating units represented by the general formula (curve) include polyα-methylstyrene, polyα-ethylstyrene, polyα-propylstyrene, polyα-butylstyrene, and the like.

The reaction is preferably carried out at a predetermined temperature using a solvent that dissolves the perfluoroalkylaryl iodonium salt represented by the general formula (IID). '11 It may be dissolved or not dissolved. In the former case, the reaction system becomes homogeneous, which is preferable in order to obtain a high perfluoroalkylation rate. In this case, it is preferable for the reaction operation that the polymer solution concentration is between 0.1% and 30% by weight.In the latter case, the reaction system will be non-uniform, but the surface layer of the raw material polymer will be This method is suitable for cases where a perfluoroalkyl group is to be introduced into only one part, and the reaction solvent can be selected according to these purposes. Examples of reaction solvents include the following and mixtures thereof. It will be done.

Methylene chloride, chloroform, carbon tetrachloride, dichloroethane, 1,1.2-)dichloro2. Otsu 1 - Halide-containing compounds such as trifluoroethane, polar solvents such as acetone, acetonitrile, dimethylformamide, dimethyl sulfoxide, nitromethane, and ethyl acetate, alcohols such as methanol and ethanol, ethers such as diethyl ether, tetrahydrofuran, and dioxane, benzene, These include hydrocarbon solvents such as toluene.

In order to prevent side reactions caused by the acid generated during the reaction, the reaction is preferably carried out in the presence of a base, and examples of the base include alkali metal alkoxides such as sodium methoxide, sodium ethoxide, and potassium t-butoxide. , metal hydrides such as sodium hydride and calcium hydride, metal hydroxides such as sodium hydroxide and potassium hydroxide, pyridine, and dimethylpyridine.

2. Organic amines such as 6-di-t-butyAl-4-methylpyridine and triethylamine, and sodium carbonate.

Metal carbonates such as potassium carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate, metal carboxylates such as potassium acetate and sodium acetate, and the like can be used. The base is used in an amount of at least an equivalent to a slight excess of the perfluoroalkylaryl iodonium salt represented by the general formula (10) used in the reaction.

The reaction temperature is -80°C to 200°C, preferably room temperature to 10°C.
A temperature range of 0°C is appropriate, and the reaction time is 1 second to 5 seconds.
More preferably, the time is between 1 minute and 30 minutes.

The polymer of the present invention obtained in this way can be
Because it has the property of preferentially causing intermolecular crosslinking reactions when irradiated with radiation such as X-rays, it can be used as a negative-type resist material against electron beams, X-rays, etc. during the manufacture of semiconductor integrated circuits.

The polymer of the present invention is excellent in sensitivity and resolution to electron beams or X-rays when used as a negative type resist material. Sensitivity (hereinafter referred to as s value) refers to the final value of residual film thickness that reaches saturation with respect to an increase in radiation dose in a sensitivity curve diagram depicting the relationship between radiation dose and residual film thickness.
It is indicated by the value of the irradiation amount corresponding to the residual film thickness, which is 0%, and the smaller the value, the higher the sensitivity. In addition, the resolution (hereinafter referred to as γ value) is 1/logl when the irradiation amount at the point where the residual film thickness is zero and the final value on the tangent line corresponding to the S value of the sensitivity curve is respectively 4 and 4. It is indicated by the value of (a, /a,), and the higher the resolution, the higher the resolution.
Published April 24th, pp. 139-140].

The S value and r value of the polymer of the present invention are several μo/cri to several tens of μa/cdt and 1.0 to 1.0, respectively, for electron beams.
2.0, xlIi! 100-200 mV/
cI/ and a value of 1.0 to 2.0, which is sufficiently high sensitivity for practical use.

It was found that it has high resolution.

Hereinafter, embodiments of the present invention will be explained in detail using Examples.

However, the description of these Examples is not intended to limit the scope of the present invention to them only, and is merely an illustrative example.

Example 1 (&) (Production and identification of perfluoroalkyl group-containing polymer) A weight average molecular weight of 4.04X was placed in a 100M eggplant-shaped flask.
104. Weight average molecular weight (M, )/number average molecular weight (Mn
) = 1.08 polyα-methylstyrene Z-mouth 9
(1.7.0 mmol in monomer unit) was taken and dissolved in 38d of tetraroform. While stirring this solution, 25 ml of acetonitrile was added dropwise to form a homogeneous solution. Furthermore, pyridine 1.37aj (17, Ommo
l) was added.

A condenser was attached to the flask, and the flask was heated to 75°C.
The temperature was raised in an oil bath. After stirring for 5 minutes, pentafluoroethyl phenyl iodonium &019 (IZOm
mol) was added little by little, and the entire amount was added over 10 minutes. After the addition, the reaction was continued for an additional 10 minutes while stirring at the same temperature.

After the reaction, the reaction solution was applied to a short column filled with silica gel and filtered using chloroform as a developing solvent. After concentrating the effluent, the concentrated solution was poured into 500 methanol to precipitate a polymer. The polymer was collected by filtration and dried by vacuum drying to obtain 1.929 of a white polymer.

It was confirmed by the following method that the obtained polymer had the structure of the following formula.

1) Infrared spectrum (KBr method) The spectrum of the polymer obtained in this example, shown by the solid line in FIG. 1a, contains 1330.・1285°1205.1
130.1090.1025,990°970,850
．． At each position of 790.725 crrr', absorptions different from the spectrum of the raw material polyα-methylstyrene, indicated by the wavy lines, appeared.

2)” P-NMR (ODol, solvent, chemical shift internal standard 01F013) 85 p as shown in Figure 1b
pm (t, 3F> and 115 ppm (m, 2
Absorption by fluorine atoms of the polymer obtained in this example appeared at each position such as F). The figure also shows a chart showing the integrated value of the peak area. Further, the pentafluoroethylation rate ("door") was measured using benzotriflate tetralide as an internal standard and was found to be α24.

3) Pyrolysis product When the polymer obtained in this example was heated, about 200%
It began to decompose at ℃.

and pentafluoroethylated α-methylsulphate repeating unit.

Note that observation by high-performance liquid chromatography revealed that the polymer obtained in this example had a molecular weight distribution almost equivalent to that of the raw material polymer.

Example 1 (b) (Electron beam sensitivity test) This Example 1 (a
The pentafluoroethylated polyα-methylstyrene 1.09 obtained in ) was dissolved in xylene 10-, the solution was applied onto a silicon wafer, and the wafer was heated at 120°C.
The mixture was brebaked in a dryer for 25 minutes.

In this way, a 154 μm pentafluoroethylated polyα-methylstyrene thin film was formed on the silicon wafer. Next, desired portions of the prebaked trench film were irradiated with an electron beam at an accelerating voltage of 20 KV at various doses. Thereafter, development was performed using xylene as a developer to dissolve and remove the portions that had not been irradiated with the electron beam, thereby forming a resist pattern on the wafer. The relationship between the electron beam dose (horizontal axis) and the remaining coating film thickness (vertical axis) at this time is shown in FIG. Hereinafter, a curve showing a similar relationship will be referred to as a sensitivity curve.

As shown in FIG. 2, the pentafluoroethylated polyα-methylstyrene obtained in Example 1 (Xun) has an 8 value and a γ value of 1.5 × 10−', which are parameters representing the performance of resist materials. It was found that it can be used as a negative type resist material with an O-po and 1.5.

Example 2 The pentafluoroethyl phenyl iodonium trifluoromethanesulfonate used in Example 1(a) was converted into aol
The procedure was carried out in the same manner as in Example 1(a), except that 2.00 g (4.25 mmol) was changed from 1.8 g to 2.00 g (4.25 mmol).
I got 19.

The infrared spectrum and IF-NMR peak positions of the obtained polymer were the same as those obtained in Example 1(a).

In addition, all of the thermal decomposition products are α-methylstyrene and pentafluoroethylated α-methylstyrene.
The pentafluoroethylation rate was measured by NMR in the same manner as in Example 1(a) and was found to be α046.

Example 3 Weight average molecular weight as poly α-methylstyrene: 2.7
x 10”, uw/1in = 1.07, 39 ml of chloroform and 2 ml of acetonitrile.
A white polymer 1,989 was obtained in the same manner as in Example 1 (~) except that the infrared spectrum of the obtained polymer was
The peak position of F-NMR was the same as that obtained in Example 1 (example 1).

Moreover, all of the thermal decomposition products were α-methylstyrene and pentafluoroethylated α-methylstyrene.

The pentafluoroethylation rate was measured by NMR in the same manner as in Example 1 (-) and was found to be 0.16.

Example 4 Poly α-methylstyrene ytoo9 (25.4 mmol in monomer unit) similar to that used in Example 1(a) was placed in 7 rasps of 2QOmt eggplant type, and chloroform 58
It was dissolved in m1. Add 17 ml of acetonitrile 5F to this solution while stirring. was added dropwise to form a uniform solution.

Furthermore, pyridine 105#Ij (25.4 mmol
) was added. A condenser was attached to the flask, and the flask was placed in a 75°C oil bath to raise the temperature. After stirring for 5 minutes, perfluoro-n-butylphenyl iodonium triple olomethane sulfonate was added little by little, and the entire amount was added over 10 minutes.

After the addition, the reaction was continued for an additional 10 minutes while stirring at the same temperature. After the reaction, the reaction solution was applied to a short column filled with silica gel and filtered using chloroform as a developing solvent. After concentrating the effluent, the concentrated solution was poured into 600 d of methanol to precipitate a polymer. The polymer was collected by filtration and dried by vacuum drying to obtain a white polymer 4.029.

It was confirmed by the following method that the obtained polymer had the structure of the following formula.

1) Infrared spectrum (KBr method) The spectrum of the polymer obtained in this example, shown by the solid line in Figure 3a, contains 1345. '1230゜1130 1
085 1QGo 980 B65840.810,7
Absorption different from the spectrum of the raw material polyα-methylstyrene indicated by the wavy line appeared at each position of 40 and 7.20 on'.

2)”?-NMR (ODOI3 solvent, chemical shift internal standard 0 FOL,) 81.7 as shown in Figure 5b.
ppm (t, 3F).

111.6ppm (m, 2F), 12A6ppm (m
, 21F).

Absorption by fluorine atoms of the polymer obtained in this example appeared at various positions such as and 1242 ppm (m, 2F). The figure also shows a chart showing the integrated value of the peak area.

Further, the perfluorobutylation rate (T÷7) was measured using benzotrifluoride as an internal standard and found to be 0.34.

5) Pyrolysis product When the white polymer obtained in this example is heated, about 2
It started to decompose at 00°C. Analysis of the decomposition products by mass spectrometry shows that all of the decomposition products are alpha-methylstyrene, which is butylated.

In addition, observation by high-performance liquid polymerography revealed that this polymer had a molecular weight distribution that was almost the same as that of the raw material polymer.

Example 5 In a 25IR1 eggplant-shaped flask, 151 μm of polyα-methylstyrene (1.28 mmol in monomer unit) similar to that used in Example 1 was added, and 3 d of tlIgform was added.
dissolved in. While stirring this solution, acetonitrile 2- was added dropwise to form a homogeneous solution.

Furthermore, pyridine (Ll 0st/(1,28mmo
l) was added. Attach a condenser to the flask,
The flask was placed in a 75°C oil path and the temperature was raised. After stirring for 5 minutes, 686 mg (1,27 mmol) of heptafluoroisopropyl-p-fluorophenyliodonium trifluorosimethanesulfonate was added little by little.
The entire amount was added in 10 minutes. After the addition, the reaction was continued for an additional 10 minutes while stirring at the same temperature.

After the reaction, the reaction solution was applied to a short column filled with silica gel and filtered using polyproform as a developing solvent. After concentrating the effluent, pour the concentrated liquid into 50-methanol,
A polymer was precipitated. The polymer was collected by filtration and dried by vacuum drying to obtain 150 cm of white polymer.

It was confirmed by the following method that the obtained polymer had the structure of the following formula.

1) Infrared spectrum (KBr method) The spectrum of the polymer obtained in this example, shown by the solid line in Figure 4a, includes 1295, 1275°, 1215.11
At each position of 60,975,950,820,715 crn'', an absorption different from the spectrum of the raw material polyα-methylstyrene indicated by a wavy line appeared.

2)”F-NMR (ODOI, solvent, chemical shift internal standard (IFOI,) 7 & 2p as shown in Figure 4b
Absorption by fluorine atoms of the polymer obtained in this example appeared at various positions such as pm (6F) and 1850 ppm (1?). The figure also shows a chart showing the integrated value of the peak area. Further, the heptafluoroisopropylation rate (i>) was measured using pencitrifluoride as an internal standard and found to be a14.

3) Pyrolysis product When the white polymer obtained in this example is heated, about 2
It began to decompose at 00°C. Analysis of the decomposition products by mass spectroscopy shows the presence of repeating units, all of which are tafluoroisopropylated α-methyl.

Furthermore, observation by high performance liquid chromatography revealed that this polymer had a molecular weight distribution that was almost the same as that of the raw material polymer.

Example 6 [Electron beam sensitivity test] Examples 2-
The electron beam sensitivity of the polymer obtained in step 5 was investigated.

As a result, as shown in Table 1, all of these polymers were found to have effective S and γ values as negative type resist materials.

[Brief explanation of drawings]

Figure 1a is an infrared absorption spectrum chart, Figure 1b is "
? -HMR absorption chart, Figure 2 is a diagram showing the sensitivity curve,
Figures 3a and 4a are infrared spectrum charts, Figure 5b,
Figure 4b is an "F-MMR absorption chart. Patent applicant: Toyo Soda Kogyo Co., Ltd. Figure 1a Figure 1b Figure 99m Figure 2 40-"10-'10-" 1n--! (C/cn
r") Figure 3a cm' Figure 3b

Claims (1)

[Claims] 1. A perfluoroalkyl group-containing polymer represented by the general formula (wherein Rf is a perfluoroalkyl group having 2 to 20 carbon atoms; R1 is carbon #li and represents an alkyl group having 1 to 5 carbon atoms; ,
X and Y each represent the number of each monomer unit in the polymer, and the value of ητ is in the range of 0.01 to 1.0).