JPH0756354A - Silicon-containing high molecular compound and resist material using the same - Google Patents

Abstract

PURPOSE:To obtain a resist material fit for fine working with far UV, KrF or ArF eximer laser light, electron beams, X-rays, etc., by using a high molecular compd. contg. ladder type polysiloxane in each of repeating units. CONSTITUTION:This resist material contains a high molecular compd. contg. ladder type polysiloxane represented by the general formula in each molecule. In the formula, each of R<1> and R<2> is 1-10C satd. alkyl, R<3> is a tetravalent arom. hydrocarbon group or a tetravalent 4-7C cyclic satd. hydrocarbon group and each of R<4>-R<7> is H or trimethylsilyl. The silicon-contg. high molecular compd. is useful as the base polymer of a photoresist because the solubility of the compd. to a solvent is varied when the compd. is irradiated with radiation such as far UV in combination with an optical acid generating agent. When this resist material is used as the upper resist of a multilayered resist, high resistance to oxygen plasma etching is ensured because of the high Si content and a pattern can precisely be transferred to the lower resist.

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 and a polymer compound containing the same and a phenylene group or the like bonded with a silicon ester in a repeating unit, and a resist material using the same. Relates to a resist material when a pattern is formed using far-ultraviolet light having a wavelength of 300 nm or less, for example, KrF excimer laser light having a wavelength of 248 nm, ArF excimer laser light having a wavelength of 193 nm, an electron beam, and an X-ray.

[0002]

2. Description of the Related Art In recent years, in the field of various electronic devices such as semiconductor devices that require fine processing, there is an increasing demand for high density and high integration of devices. Miniaturization is becoming essential. One of the methods for making the pattern finer is to shorten the wavelength of the exposure light used when forming the 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 the wavelength λ of the exposure light in lithography may be shortened in order to obtain a higher resolution, that is, the value of RS.

Currently, for manufacturing a dynamic random access memory (DRAM) having a degree of integration of, for example, up to 64M, a line and space resolution of a minimum pattern size of 0.35 μm is required, and a g line (438) of an Hg lamp is required.
nm) and i-line (365 nm) are used as the light source. In order to manufacture a DRAM having a degree of integration of 256M or more, a finer processing technique (processing dimension is 0.25 μm or less) is required, which is why an excimer laser (KrF: 2) is used.
48nm, ArF193nm) shorter wavelength light (D
eeep UV light) is considered to be effective, especially K
rF lithography has been actively studied. But,
The shortening of the wavelength of the light source causes a problem that the depth of focus represented by DOF = λ / NA ² (DOF: depth of focus) is reduced. Further, in the advanced development and trial manufacture of the device, the fine processing on the substrate becomes complicated and precise, so that the step difference on the substrate becomes large, and it becomes difficult to form a pattern by the conventional single layer process. A multilayer resist method has been proposed as a method for solving these problems. In this method, a material that is easily dry-etched by oxygen plasma, such as phenol novolac resin or cresol novolac resin, is spin-coated to flatten the substrate, and then a pattern is formed with a resist having oxygen-resistant dry etching resistance. Then, the pattern is transferred to the lower layer by anisotropic etching using oxygen plasma. Furthermore, 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 investigated. Resist materials having silicon atoms have excellent resistance to oxygen plasma etching, and various silicon-containing resist materials have been reported so far. In particular, since ladder-type polysiloxane has characteristics such as high silicon content and excellent thermal stability, a resist material using the same has been actively researched. For example, the acetyl group and / or the acetyl group described in JP-A-4-36755 and the like.
Alternatively, a resist material containing an alkali-soluble polysilsesquioxane containing a hydroxyl group as a main component can be used.

Further, the resist material used for microfabrication has high resolution corresponding to the miniaturization of machining dimensions,
The demand for higher sensitivity is also increasing. This is because the use of an expensive excimer laser as the light source requires improvement in cost performance. Currently, chemically amplified resists using photoacid generators are being actively researched because they can be expected to dramatically improve sensitivity (eg, Hiroshiito, C. Grant Wilson, American Chemical Society Symposium. Series (Hiroshi Ito, C. Grant Wi
llson, American Chemical S
(Ociety Symposium Series),
242, pp. 11-23 (1984)). In this method, a protonic acid generated from a photo-acid generator by exposure is moved in a solid phase of a resist by a heat treatment, and a chemical change to a resist resin caused thereby is catalytically amplified several hundred to several thousand times. Is characterized by.

[0005]

However, there have been few examples of ladder-type polysiloxanes or polymer compounds containing ladder-type polysiloxanes in their molecules, which have been 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 photo-acid generator.

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

[0007]

As a result of earnest research, the inventors have found that the above technical problems can be solved by a novel polymer compound represented by the following general formula (I), and completed the present invention.

[0008]

[Chemical 2]

In the formula, R ¹ and R ² may be the same or different and each represents a saturated alkyl group having 1 to 10 carbon atoms (more specifically, a methyl group, an ethyl group, an n-propyl group, It represents a 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 base having the following structure. ),

[0010]

[Chemical 3]

R ⁴ , R ⁵ , R ⁶ and R ^{7, which} may be the same or different, each represents a hydrogen atom or a trimethylsilyl group. n is a positive integer of 3 to 50, m is 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, for example, by the following method. A terminal hydroxyl group 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
I) an acid halide (wherein R ³ is as defined above, X is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom) in toluene, tetrahydrofuran, chloroform or the like (preferably toluene); : 0.7-1: 1.5
(More preferably 1: 0.9 to 1: 1.1) and mixed and dissolved in a molar ratio. A base (for example, pyridine, triethylamine, N, N-dimethylaniline, etc.) is added thereto,
In an argon atmosphere, 10 ° C to 100 ° C (preferably 2
0.5 to 10 hours (preferably 3 to 6) at 0 ° C to 40 ° C
Time) to react. After the 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.
Further, after this, the terminal hydroxyl group is trimethylsilylated with a silylating agent such as hexamethyldisilazane to obtain a polymer compound of the general formula (I) having a terminal trimethylsilyl group.

[0013]

[Chemical 4]

It has been confirmed that these polymer 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 the polymer compound represented by is used as a base polymer of a resist, it is combined with a photo acid generator such as triphenylsulfonium salt, diphenyliodonium salt or o-nitrobenzyl tosylate, and deep UV light (deep UV light) is used. By irradiating the polymer with an acid generated from the photoacid generator, the Si—O bond of the silicon ester in the polymer compound represented by the general formula (I) is cleaved, that is, the main chain of the polymer compound (I) is broken. Disconnection occurs. This allows
Since the solubility of the exposed portion in a 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 high silicon content results in high oxygen plasma etching resistance and reactive ion etching treatment using oxygen gas. Thus, the pattern can be accurately transferred to the lower layer resist.

[0015]

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

[0016]

[Table 1]

Reference Example 1 An example of the synthesis of terminal hydroxyl group polyisobutylsilsesquioxane 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 cooled to 0 to 10 ° C. With vigorous stirring, a solution prepared by dissolving 10 ml (0.07 mol) of isobutyltrichlorosilane in 75 ml of diethyl ether was added dropwise over 15 minutes, and 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 with diethyl ether three times. The previously separated diethyl ether layer and the extract were combined, washed with saturated saline, and then dried over anhydrous magnesium sulfate for 12 hours, and the solvent was distilled off under reduced pressure. As a result, 14 g of colorless and transparent terminal hydroxyl group polyisobutylsilsesquioxane was obtained (yield 84%). The structure of the target substance 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. Shimadzu LC-9A is used for molecular weight measurement and Shimadzu S is used for detection.
Using PD-6A, using tetrahydrofuran as a solvent and using a GPC column (GPC KF-80M) manufactured by Showa Denko,
It was determined as a molecular weight in terms of polystyrene. ¹ H-NMR (CDCl ₃ , internal standard substance: 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) (1 H-NMR methylene group and a hydroxyl group intensity ratio of the spectrum of the terminal hydrogen groups polyisobutyl silsesquioxane degree of polymerization is 5.6.) IR (Liquid film method, cm ^-1 ) 1100
(Ν _si-o-si ) Weight average molecular weight: 1620 Elemental analysis C H Si actual value (wt%) 44.07 8.88 20.92 Theoretical value (wt%) 44.83 8.67 21.42 (implementation) Example 1) 0.70 g of terminal hydroxypolyisobutylsilsequioxane (polymerization degree: 5.6) synthesized in Reference Example 1 was dissolved in 20 ml of dry toluene in a 100 ml flask, 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 acid chloride was added once every 30 minutes in 5 batches. After 4 hours from the start of the reaction, the precipitate formed from the reaction mixture was removed by filtration, and the filtrate was added with methanol 500.
It poured into ml and reprecipitated. The white precipitate thus deposited was collected by filtration and depressurized for 12 hours to obtain 0.69 g of a polymer compound (yield 87%). ¹ H-NMR (CDCl ₃ , internal standard substance: 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 (ν _{c = o} ) Weight average molecular weight: 8200 Elemental analysis CH 2 Si 5 Measured value (wt%) 48.22 7.35 18.68 Theoretical value (wt%) 48.74 7. 63 19.04 (Example 2) Synthesis was carried out by the method of Example 1, except that dry pyridine was used instead of dry toluene as the solvent in which the terminal hydroxypolyisobutylsilsesquioxane was first dissolved (yield 83 %). The structure of the target product was confirmed by the same method as in Example 1. ¹ H-NMR (CDCl ₃ , internal standard substance: 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 (ν _{c = o} ) Weight average molecular weight: 16600 Elemental analysis CH 2 Si 5 Measured value (wt%) 48.44 7.20 18.88 Theoretical value (wt%) 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 substance: 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 (ν _{c = o} ) Weight average molecular weight: 51900 Elemental analysis CH 2 Si 5 Measured value (wt%) 48.66 7.35 18.65 Theoretical value (wt%) 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. . Then, it heated at 70 degreeC, stirring, and performed reaction for 2 hours. After completion of the reaction, this 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 end-capped with a trimethylsilyl group (yield 91. 3%). The structure of the target product was analyzed by the same method as in Example 1. ¹ H-NMR (CDCl ₃ , internal standard substance: 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 (ν _{c = o} ) Weight average molecular weight: 8000 Elemental analysis C H Si actual value (wt%) 48.93 6.90 19.60 Theoretical value (wt%) 49.65 7. 09 19.83 (Example 5) Terminal hydroxy polyisobutyl silsesquioxane (polymerization degree 24.5) in a 100 ml flask.
1.54 g was dissolved in 20 ml of dry toluene, and
0.5 ml of dry pyridine was added and it was heated to 50 ° C. There, 0.095 g (0.0003mo) of 1,2,3,4- cyclopentane tetracarboxylic acid chloride
5 ml of the dry toluene solution of 1) is added once per 1 ml 30
It was added 5 times every minute. After 4 hours from the start of the reaction, the 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 white precipitate thus deposited was recovered and depressurized for 12 hours to obtain 1.29 g of a polymer compound (yield 8
2%). The structure of the target product was confirmed by the same method as in Example 1. ¹ H-NMR (CDCl ₃ , internal standard substance: 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 (ν
_si-o-si ), 1718 (ν _{c = o} ) Weight average molecular weight: 23800 Elemental analysis C H Si Actual value (wt%) 46.37 8.03 21.29 Theoretical value (wt%) 46.83 8. 39 21.33 (Example 6) Japanese Patent Application Laid-Open No. 53-8
Terminal hydroxypolymethylsilsesquioxane (polymerization degree 10.2) synthesized according to the synthesis example described in 8099.
0.62 g was dissolved in 20 ml of dry toluene, and
0.5 ml of dry pyridine was added and it was heated to 50 ° C. 0.19 g of pyromellitic acid chloride there
5 ml of a dry toluene solution of (0.00058 mol) was added every 1 minute in 5 batches every 30 minutes. After 4 hours from the start of the reaction, the 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 white precipitate thus deposited was collected and dried under reduced pressure for 12 hours to obtain 0.63 g of a polymer compound (yield 87%). The structure of the target product was confirmed by the same method as in Example 1. ¹ H-NMR (CDCl ₃ , internal standard substance: 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 (ν _{c = o} ) Weight average molecular weight: 15500 Elemental analysis CH 2 Si 4 Measured value (wt%) 24.87 4.03 31.72 Theoretical value (wt%) 25.14 4. 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 toluene solution of 1N p-toluenesulfonic acid was added thereto. 1 cc was added and heated at 80 ° C. for 10 minutes with stirring. The solution was washed 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 added to 80 g of methyl isobutyl ketone.
g and then filtered with a 0.2 μm pore membrane filter, and the resulting solution has a film thickness of 1 μm on a silicon substrate.
Was spin-coated on a hot plate and prebaked at 120 ° C. for 90 seconds. This was immersed in ethanol and the dissolution rate of the membrane was measured. Next, the film prepared under the same conditions was irradiated with KrF excimer laser (MEX excimer laser manufactured by NEC Corporation) (exposure amount: 30 mJ · cm ⁻¹ ) and then post-baked at 110 ° C. for 60 seconds, followed by ethanol conversion. It was dipped and the dissolution rate of the membrane was measured. As a result, the dissolution rate of the film after exposure was about 150 times that before exposure.

In this embodiment, R is used for simplicity.
^1, R ^2, but R ⁴ to R ⁷ showed only of the same substituents, necessarily R ¹ in the present invention and R ^2, R ⁴ ~R ⁷
Do not need to be the same, and similar effects were obtained even when compounds having different substituents were included.

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

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

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Etsuo Hasegawa 5-7-1, Shiba, Minato-ku, Tokyo Inside NEC Corporation

Claims (2)

[Claims] 1. The following general formula (I): In the formula, R ¹ and R ² may be the same or different and each represents 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, 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 3 to 50 and m is 2 to
A silicon-containing polymer compound having a positive integer of 100. 2. A resist material comprising the polymer compound according to claim 1 and a photosensitive compound capable of generating an acid upon exposure.