JP2606652B2 - Silicon-containing polymer compound and resist material using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ladder type polysiloxane in a repeating unit, a high molecular weight compound containing a phenylene group and the like linked by a silicon ester in a repeating unit, and a resist material using the same. The present invention relates to a resist material for forming a pattern by using far ultraviolet light of 300 nm or less as an exposure source, for example, KrF excimer laser light of 248 nm, ArF excimer laser light of 193 nm, electron beam, X-ray, or the like.

[0002]

2. Description of the Related Art In recent years, in the field of various electronic devices that require fine processing such as semiconductor devices, the demand for high density and high integration of devices has been increasing. Miniaturization has become essential. One method of miniaturizing a pattern is to shorten the wavelength of exposure light used in forming a photoresist pattern. Generally, the resolution RS of the optical system is R
S = k · λ / NA (where λ is the wavelength of the exposure light source, NA is the numerical aperture of the lens, and k is the process factor). From this equation, it can be seen that higher resolution, that is, a smaller value of RS may be achieved by shortening the wavelength λ of the exposure light in lithography.

At present, the production of a dynamic random access memory (DRAM) having a degree of integration of up to 64 M requires a line and space resolution of a minimum pattern size of 0.35 μm and a g-line (438) of an Hg lamp.
nm) and i-line (365 nm) are used as light sources. In order to manufacture a DRAM having an integration degree of 256M or more, a finer processing technology (processing size of 0.25 μm or less) is required. Therefore, an excimer laser (KrF: 2
48 nm, ArF 193 nm) or other shorter wavelength light (D
deep UV light) is considered to be effective.
rF lithography is being actively studied. But,
Shortening the wavelength of the light source causes a problem of reducing the depth of focus represented by DOF = λ / NA ² (DOF: depth of focus). Also, in advanced development prototypes of devices, fine processing on the substrate becomes complicated and precise, so that the steps on the substrate become large, and it becomes difficult to form a pattern by the conventional single-layer process. As a method for solving these problems, a multilayer resist method has been proposed. In this method, a material that is easily dry-etched by oxygen plasma, such as a phenol novolak resin or a cresol novolak resin, is spin-coated, the substrate is flattened, and a pattern is formed using a resist having oxygen-resistant dry-etching properties. Then, the pattern is transferred to the lower layer by anisotropic etching using oxygen plasma. Further, since a resist pattern having a high aspect ratio can be obtained by this method, a resist material having oxygen plasma etching resistance has been actively studied. Resist materials having silicon atoms are excellent in oxygen plasma etching resistance, and various silicon-containing resist materials have been reported so far. In particular, ladder-type polysiloxanes have characteristics such as a high silicon content and excellent thermal stability. Therefore, resist materials using the same have been actively studied. For example, an acetyl group and / or an acetyl group described in JP-A-4-36755 and the like can be used.
Alternatively, a resist material containing an alkali-soluble polysilsesquioxane containing a hydroxyl group as a main component can be used.

[0004] Further, in addition to high resolution corresponding to miniaturization of processing dimensions, resist materials used for microprocessing are required.
The demand for higher sensitivity is increasing. This is because the use of an expensive excimer laser as a light source requires an improvement in cost performance. At present, chemically amplified resists using a photoacid generator are being actively studied because a dramatic improvement in sensitivity can be expected (for example, Hiroshito, C. Grant Wilson, American Chemical Society Symposium. Series (Hiroshi Ito, C. Grant Wi
llson, American Chemical S
environment Symposium Series),
242, pp. 11-23 (1984)). In this method, the protonic acid generated from the photoacid generator by exposure is moved in the resist solid phase by heat treatment, and the chemical change to the resist resin is amplified catalytically by several hundred to several thousand times. It is characterized by.

[0005]

However, ladder-type polysiloxanes or high-molecular compounds containing ladder-type polysiloxanes in their molecules have been rarely used as chemically amplified resists. The reason is that there has been almost no change in solubility in a developer due to a chemical change due to a protonic acid generated from a photoacid generator.

An object of the present invention is to develop a ladder-type polysiloxane or a polymer compound containing a ladder-type polysiloxane in a molecule whose solubility is easily changed by a protonic acid generated from a photoacid generator.

[0007]

Means for Solving the Problems As a result of intensive studies, the inventors have found that the above technical problem can be solved by a novel polymer compound represented by the following general formula (I), and have reached the present invention.

[0008]

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In the formula, R ¹ and R ² may be the same or different and represent a saturated alkyl group having 1 to 10 carbon atoms (more specifically, a methyl group, an ethyl group, an n-propyl group, sec-propyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, decanyl group, etc.). R ³ is an aromatic hydrocarbon tetravalent group, a cyclic saturated hydrocarbon tetravalent group having 4 to 7 carbon atoms (more specifically,
It represents a group having the following structure . ).

[0010]

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R ⁴ , R ⁵ , R ⁶ and R ⁷ may be the same or different and represent a hydrogen atom or a trimethylsilyl group. n is a positive integer of 3 to 50, m is a positive integer of 2 to 100 (more preferably, n is 3 to 20, and m is 3 to 30).

The polymer compound according to the present invention is synthesized by, for example, the following method. A hydroxyl-terminated ladder-type polysiloxane represented by the general formula (II) (wherein R ¹ and R ² are
Same as above. n is a positive integer of 3 to 50) and the general formula (II
The acid halide represented by I) (wherein R ³ is the same as described above; X is a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom) is added to toluene, tetrahydrofuran, chloroform or the like (preferably toluene). : 0.7 to 1: 1.5
(More preferably, 1: 0.9 to 1: 1.1) are mixed and dissolved in a molar ratio. A base (eg, pyridine, triethylamine, N, N-dimethylaniline, etc.) is added thereto,
10 ° C to 100 ° C (preferably 2 ° C) in an argon atmosphere
(0 ° C to 40 ° C) for 0.5 to 10 hours (preferably 3 to 6 hours)
Time) to react. After completion of the reaction, the salt produced by filtration is removed, the filtrate is poured into methanol, and the deposited precipitate is collected by filtration and dried under reduced pressure to obtain the desired product.
Thereafter, when the terminal hydroxyl group is trimethylsilylated with a silylating agent such as hexamethyldisilazane, a polymer compound of the general formula (I) having a terminal trimethylsilyl group is obtained.

[0013]

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It has been confirmed that these high molecular compounds are easily decomposed by an acid such as p-toluenesulfonic acid, hydrochloric acid or sulfuric acid to lower the molecular weight. General formula (I)
When a polymer compound represented by the formula (1) is used as a resist base polymer, a deep UV light (deep UV light) is used in combination with a photoacid generator such as triphenylsulfonium salt, diphenyliodonium salt or o-nitrobenzyl tosylate. To cleave the Si—O bond of the silicon ester in the polymer compound represented by the general formula (I) by the acid generated from the photoacid generator, ie, the main chain of the polymer compound (I) Disconnection occurs. This allows
Since the solubility of the exposed part in the solvent changes greatly, a resist pattern can be obtained by developing with an appropriate solvent. That is, when the polymer compound represented by the general formula (I) is used as an upper layer resist of a multi-layer resist, its silicon content is high, so that oxygen plasma etching resistance is high, and reactive ion etching using oxygen gas is performed. Accordingly, the pattern can be transferred to the lower resist with high accuracy.

[0015]

Examples Examples of the compounds of the present invention are described below. However, Examples 1 to 6 are synthesis examples of the polymer compound represented by the general formula (I), and R ^{1 to} R ⁷ are shown in Table 1.

[0016]

[Table 1]

Reference Example 1 An example of synthesizing polyisobutylsilsesquioxane having a terminal hydroxyl group is shown below.

In a 300 ml three-necked reactor, 17 g (0.21 mol) of sodium hydrogencarbonate was added to a mixed solution of 25 ml of water and 50 ml of diethyl ether, and the mixture was cooled to 0 to 10 ° C. While stirring vigorously, a solution of 10 ml (0.07 mol) of isobutyltrichlorosilane dissolved in 75 ml of diethyl ether was added dropwise to the solution over 15 minutes, and the stirring was continued for 2 hours. After completion of the reaction, the reaction mixture was separated into a diethyl ether layer and an aqueous layer, and the aqueous layer was extracted three times with diethyl ether. The extracted diethyl ether layer and the extract were combined, washed with saturated saline, dried over anhydrous magnesium sulfate for 12 hours, and the solvent was distilled off under reduced pressure. Thus, 14 g of a colorless and transparent polyisobutylsilsesquioxane having a terminal hydroxyl group was obtained (yield: 84%). The structure of the target product was confirmed by ¹ H-NMR measurement (AMX-400 type NMR apparatus manufactured by Bruker), IR measurement (IR-470 manufactured by Shimadzu), elemental analysis and the like. For molecular weight measurement, use Shimadzu S-9 to detect LC-9A.
Using PD-6A, GPC column (GPC KF-80M) manufactured by Showa Denko using tetrahydrofuran as a solvent,
It was determined as the molecular weight in terms of polystyrene. ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane): δ (ppm) 0.45 to 0.85 (w, 2H, Si—CH ₂ —),
_{0.85~1.10 (w, 3H, -CH 3} ) 1.50~2.05 (m, 1H, -CH), 5.05~
5.20 (s, 0.36H, -OH) (The degree of polymerization of the terminal hydrogen group polyisobutylsilsesquioxane is 5.6 from the intensity ratio of the methylene group to the hydroxyl group in the ¹ H-NMR spectrum.) IR (Liquid film method, cm ^-1 ) 1100
(Ν _{si -o-si} ) Weight average molecular weight: 1620 Elemental analysis CH Si Actual value (% by weight) 44.07 8.88 20.92 Theoretical value (% by weight) 44.83 8.67 21.42 (Implementation Example 1) In a 100 ml flask, 0.70 g of terminal hydroxy polyisobutylsilsequioxane (degree of polymerization 5.6) synthesized in Reference Example 1 was dissolved in 20 ml of dry toluene, and 0.5 ml of dry pyridine was added. This was heated to 50 ° C. To this, 5 ml of a dry toluene solution of 0.19 g (0.00058 mol) of pyromellitic chloride was added 5 times every 30 minutes in 1 ml portions. After 4 hours from the start of the reaction, the precipitate formed from the reaction mixture was removed by filtration, and the filtrate was subjected to methanol 500
The solution was poured into the resulting solution for reprecipitation. The precipitated white precipitate was collected by filtration and reduced in pressure for 12 hours to obtain 0.69 g of a polymer compound (87% yield). ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane): δ (ppm) 0.45 to 0.85 (w, 2H, Si—CH ₂ —),
_{0.85~1.10 (w, 3H, -CH 3} ) 1.50~2.05 (m, 1H, -CH), 7.95
(S, 0.18H, aromatic) IR (KBr tablet, cm ^-1 ) 1100 (ν
_si-o-si ), 1718 (v _{c = o} ) Weight average molecular weight: 8200 Elemental analysis CH Si Actual value (% by weight) 48.22 7.35 18.68 Theoretical value (% by weight) 48.74 7. 63 19.04 (Example 2) The synthesis was carried out in the same manner as in Example 1, except that a solvent for dissolving terminal hydroxypolyisobutylsilsesquioxane was replaced with dry pyridine instead of dry toluene (yield: 83). %). The structure of the target was confirmed in the same manner as in Example 1. ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane): δ (ppm) 0.45 to 0.85 (w, 2H, Si—CH ₂ —),
_{0.85~1.10 (w, 3H, -CH 3} ) 1.50~2.05 (m, 1H, -CH), 7.95
(S, 0.18H, aromatic) IR (KBr tablet, cm ^-1 ) 1100 (ν
_si-o-si ), 1718 (v _{c = o} ) Weight average molecular weight: 16600 Elemental analysis CH Si Actual value (% by weight) 48.44 7.20 18.88 Theoretical value (% by weight) 48.74 7. 63 19.04 (Example 3) Synthesis was carried out by the method of Example 1 except that 0.5 g of 4-N, N-dimethylaminopyridine was used instead of pyridine (yield: 92%). ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane): δ (ppm) 0.45 to 0.85 (w, 2H, Si—CH ₂ —),
_{0.85~1.10 (w, 3H, -CH 3} ) 1.50~2.05 (m, 1H, -CH), 7.95
(S, 0.18H, aromatic) IR (KBr tablet, cm ^-1 ) 1100 (ν
_si-o-si ), 1718 (v _{c = o} ) Weight average molecular weight: 51900 Elemental analysis CH Si Actual value (% by weight) 48.66 7.35 18.65 Theoretical value (% by weight) 48.74 7. 63 19.04 (Example 4) In a 100 ml three-necked flask, 0.8 g of the polymer compound obtained in Example 2 was dissolved in 5 ml of dry tetrahydrofuran, and 0.2 ml of hexamethyldisilazane was added thereto. . Thereafter, the mixture was heated to 70 ° C. with stirring and reacted for 2 hours. After completion of the reaction, the mixture was poured into dry methanol, and the deposited precipitate was collected and dried under reduced pressure for 12 hours to obtain 0.73 g of a polymer compound having a terminal end-capped with a trimethylsilyl group (yield 91. 3%). The structure of the target was analyzed in the same manner as in Example 1. ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane): δ (ppm) 0.45 to 0.85 (w, 2H, Si—CH ₂ —),
_{0.85~1.10 (w, 3H, -CH 3} ) 1.50~2.05 (m, 1H, -CH), 7.95
(S, 0.18H, aromatic) IR (KBr tablet, cm ^-1 ) 1100 (ν
_si-o-si ), 1718 (vc _{= o} ) Weight average molecular weight: 8000 Elemental analysis CH Si Actual value (% by weight) 48.93 6.90 19.60 Theoretical value (% by weight) 49.65 7. 09 19.83 (Example 5) In a 100 ml flask, terminal hydroxy polyisobutylsilsesquioxane (polymerization degree: 24.5)
1.54 g was dissolved in dry toluene 20 ml.
0.5 ml of dry pyridine was added and this was heated to 50 ° C. There, 0.095g of 1,2,3,4-cyclopentanetetracarboxylic acid chloride (0.0003mo
1) 5 ml of the dry toluene solution of l)
Added in 5 portions every minute. After 4 hours from the start of the reaction, the reaction mixture was cooled to room temperature, the precipitate formed from the reaction mixture was removed by filtration, and the filtrate was poured into 500 ml of methanol for reprecipitation. The precipitated white precipitate was collected and reduced in pressure for 12 hours to obtain 1.29 g of a polymer compound (yield: 8).
2%). The structure of the target was confirmed in the same manner as in Example 1. ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane): δ (ppm) 0.45 to 0.85 (w, 2H, Si—CH ₂ —),
_{0.85~1.10 (w, 3H, -CH 3} ) 1.50~2.05 (m, 1H, -CH), 3.15~
4.25 (m, 0.0H, -CH2-, -CH) IR (KBr tablet, cm ^-1 ) 1100 (v
_si-o-si ), 1718 (v _{c = o} ) Weight average molecular weight: 23800 Elemental analysis CH Si Actual value (% by weight) 46.37 8.03 21.29 Theoretical value (% by weight) 46.83 8. 39 21.33 (Example 6) Japanese Patent Application Laid-Open No. 53-8 / 100
8099 terminal hydroxy polymethyl silsesquioxane synthesized according to the synthesis example described in 8099 (degree of polymerization 10.2)
0.62 g was dissolved in dry toluene 20 ml.
0.5 ml of dry pyridine was added and this was heated to 50 ° C. There, 0.19 g of pyromellitic chloride
(0.00058 mol) of a dry toluene solution (5 ml) was added in 5 portions every 30 minutes in 1 ml portions. After 4 hours from the start of the reaction, the reaction mixture was cooled to room temperature, the precipitate formed from the reaction mixture was removed by filtration, and the filtrate was poured into 500 ml of methanol for reprecipitation. The precipitated white precipitate was recovered and dried under reduced pressure for 12 hours to obtain 0.63 g of a polymer compound (yield 87%). The structure of the target was confirmed in the same manner as in Example 1. ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane): δ (ppm) 0.45 to 0.60 (s, 1H, Si—CH ₃ —),
7.95 (5, 0.03H, aromatic) 1.50 to 2.05 (m, 1H, -CH), 7.95
(S, 0.18H, aromatic) IR (KBr tablet, cm ^-1 ) 1100 (ν
_si-o-si ), 1718 (v _{c = o} ) Weight average molecular weight: 15500 Elemental analysis CH Si Actual value (% by weight) 24.87 4.03 31.72 Theoretical value (% by weight) 25.14 34 32.30 (Example 7) In a beaker, 1 g of the polymer compound (weight average molecular weight: 16600) obtained in Example 2 was dissolved in 10 g of toluene, and a 1N toluene solution of p-toluenesulfonic acid was added thereto. 1 cc was added and heated at 80 ° C. for 10 minutes with stirring. After washing this solution with water, the solvent was distilled off under reduced pressure, and the molecular weight was measured by GPC. As a result, the weight average molecular weight was reduced from 16600 to 1880, and it was confirmed that the molecular weight was reduced by the acid.

Example 8 18 g of the polymer compound obtained in Example 2 and 2 g of triphenylsulfonium trifluoromethanesulfonate were mixed with 80 g of methyl isobutyl ketone.
g, filtered through a 0.2 μm pore membrane filter, and the resulting solution was coated on a silicon substrate to a thickness of 1 μm.
And prebaked on a hot plate at 120 ° C. for 90 seconds. This was immersed in ethanol, and the dissolution rate of the film was measured. Next, the film formed under the same conditions was irradiated with a KrF excimer laser (MEX excimer laser manufactured by NEC Corporation) (exposure amount: 30 mJ · cm ⁻¹ ), followed by post-baking at 110 ° C. for 60 seconds, and ethanol. After immersion, the dissolution rate of the film was measured. As a result, the dissolution rate of the film after exposure was about 150 times that before exposure.

In this embodiment, for simplicity, R
^{Although only} R ¹ , R ² and R ^{4 to} R ⁷ have the same substituent, R ¹ and R ² , R ^{4 to} R ⁷ are not necessarily required in the present invention.
Need not be the same, and the same effect can be obtained even when compounds having different substituents are contained.

As described above, when the silicon-containing polymer compound of the present invention is combined with a photoacid generator and is irradiated with radiation such as far ultraviolet light, the solubility in a solvent is significantly changed. It has been found useful as a base polymer.

Further, the silicon-containing polymer compound of the present invention comprises:
Since it has a silicon atom in the molecule, it has good oxygen plasma resistance and is effective for use in a photoresist.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Etsuo Hasegawa 5-7-1 Shiba, Minato-ku, Tokyo Within NEC Corporation (56) References JP-A-1-105156 (JP, A) JP-A-3 -100553 (JP, A) JP-A-5-11451 (JP, A)

Claims (2)

(57) [Claims] 1. A compound represented by the following general formula (I): Wherein R ¹ and R ² may be the same or different and represent a saturated alkyl group having 1 to 10 carbon atoms;
³ represents an aromatic hydrocarbon tetravalent group or a cyclic saturated hydrocarbon tetravalent group having 4 to 7 carbon atoms, and R ⁴ , R ⁵ , R ⁶ , R
⁷ may be the same or different and represents a hydrogen atom or a trimethylsilyl group, n is 3 to 50, and m is 2 to
A silicon-containing polymer compound that is a positive integer of 100. 2. A resist material comprising both the polymer compound according to claim 1 and a photosensitive compound which generates an acid upon exposure.