JP2682417B2 - Silicon-containing sulfonium salt compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to novel cationic cation polymerization initiators and novel silicon-containing sulfonium salt compounds useful in photolithography.

[0002]

2. Description of the Related Art Examples of conventional sulfonium salts include triarylsulfonium salts described in US Pat. No. 4,374,066 and diaryl iodonium salts described in US Pat. No. 4,264,703. These have been used as photocationic polymerization initiators (photoacid generators). Further, these sulfonium salts have recently been applied as a photosensitizer for a photoresist (chemically amplified resist) in a photolithography process for manufacturing a super integrated circuit.

On the other hand, with the high density and high integration of semiconductor devices, fine processing technology (processing dimension is 0.25 μm or less)
Is required, and for that reason, an excimer laser (KrF:
It is considered that shorter wavelength light (deep ultraviolet (DeepUV) light) such as 248 nm and ArF193 nm) is effective.

[0004]

However, conventional photo-acid generators such as the above-mentioned triarylsulfonium salts and diaryliodonium salts are generally compounds having an aromatic ring such as benzene and have a short wavelength region of 200 nm or less. Is too large to absorb the above-mentioned light and cannot be used for a photosensitive composition (for example, a chemically amplified resist) using short-wavelength light of 200 nm or less such as ArF excimer laser (wavelength 193 nm). was there. Further, a compound in which the photo-acid generator itself has effective resistance to a dry etching process using oxygen plasma has not been obtained.

An object of the present invention is a silicon-containing sulfonium salt compound which is highly transparent to short-wavelength light of 200 nm or less (for example, ArF excimer laser) and can be a photo-acid generator having high dry etch resistance to oxygen plasma. Is to provide.

[0006]

As a result of earnest research by the inventor, the above technical problem is represented by the following general formula (I) obtained from a silicon-containing polymer, an organic acid metal salt and an alkyl halide. The present invention was found to be solved by a novel silicon-containing sulfonium salt compound described above.

[0007]

Embedded image

Here, n is a positive integer of 1 to 300 (more preferably a positive integer of 20 to 150), and R ¹ and R
² is a linear, branched, or cyclic alkylene group having 2 to 10 carbon atoms (for example, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, cyclohexylene group, etc.), R ³ is 3 to 7 carbon atoms. 2-oxoalkyl group (for example, 2-oxopropyl, 2-oxobutyl,
2-oxopentyl, 2-oxohexyl, 2-oxocyclopentyl, 2-oxocyclohexyl, 2-oxocycloheptyl group and the like). Y ^- is BF ₄ ^-, As
F ₆ ⁻ , SbF ₆ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , Cl
^{-, Br -, I -,} ClO 4 -, CH 3 SO 3 - non-nucleophilic counter anion such as, Z represents a hydrogen atom or a trimethylsilyl group. However, as Y ⁻ , BF ₄ ⁻ and AsF _{6
^{-, SbF 6 -, PF 6}} - or CF ₃ SO ₃ ^- is more preferable. X is the general formula (II) or the general formula (II
I) (however, m is 1 to 100, and more preferably 1
Is a positive integer of 50 to 50).

[0009]

[0010]

Embedded image

Here, R ⁴ and R ⁵ are alkyl groups having 1 to 8 carbon atoms (for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl groups, etc.) or phenyl groups.

The silicon-containing sulfonium salt compound represented by the general formula (I) is, for example, Journal of the Organic Chemistry (Journal of the chemistry).
Organic Chemistry) Volume 57 (2
No.), pp. 759-761 (1992) for low molecular weight onium salts (Reiser).
It is produced by applying the above method and subjecting the corresponding silicon-containing sulfide compound to a sulfonation reaction. That is, for example, it is manufactured as follows. A silicon-containing polymer represented by the general formula (IV) (wherein R ¹ , R ² , X, n,
m is the same as above, and general formula (V) (wherein R ³ is the above,
W includes iodine, bromine, chlorine atom and the like), and an alkyl halide represented by the general formula (VI) (in the formula, M ⁺ is K ⁺ , Na ⁺ ,
(Ag ⁺ and Y are the same as above), and have an equimolar ratio or an alkyl halide (V) in terms of the sulfide group of the general formula (IV).
Mix in a small excess molar ratio (compound (V) / compound (IV) sulfide group molar ratio: 1.0 to 1.5) and react in methylene chloride or nitromethane at room temperature to solvent reflux temperature for 3 to 12 hours. After completion of the reaction, the insoluble metal salt is filtered off, and the filtrate is reprecipitated in, for example, ether to obtain the compound represented by the general formula (I).

It is also possible to synthesize a compound (I) derivative having a sulfonium residue ratio of less than 1.0 by mixing less than equimolar amount of compound (V) with respect to the sulfide unit of compound (IV) and reacting in the same manner. Is.

The compound represented by the general formula (IV) is synthesized, for example, by the method shown below. General formula (VI
I) (wherein R ⁴ , R ⁵ and m are the same as above), or a silane or siloxane derivative represented by the general formula (VIII) (wherein R ⁴ , R ⁵ and m are the same as above), and Ω, ω′-thiodialkanol represented by the general formula (IX) (for example, 2,2′-thiodiethanol or 3,
3'-thiodipropanol or a mixture thereof) in an equimolar ratio in dry pyridine, and then heated under reflux for 1 to 6 hours under an argon atmosphere and then cooled, and the reaction mixture is reprecipitated in methanol. Gives an intermediate compound represented by the general formula (IV).

The compound of the general formula (I) in which Z is a trimethylsilyl group is synthesized by the following method. That is, the compound of the general formula (I
For example, a compound represented by the formula (I) in which Z is a hydrogen atom can be prepared by subjecting a compound represented by V) to trimethylsilylation of hydroxyl groups at both terminals with a silylating agent such as hexamethyldisilazane in dry tetrahydrofuran. The compound of the general formula (I) in which Z is a trimethylsilyl group can be obtained by sulfoniumization in the same manner as in the case.

[0016]

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When a group other than a phenyl group is used as R ⁴ and R ⁵ , transparency to deep ultraviolet light (deep UV light) having light absorption for benzene rings such as KrF and ArF excimer lasers. Is higher.

Far-ultraviolet light, excimer laser (KrF (248n
m), ArF (193 nm), etc.) was confirmed to generate an acid. Furthermore, the polymer compound of the present invention undergoes acid hydrolysis (conversion of silyl ether to silanol) due to an acid generated by heating after irradiation with light, thereby significantly changing the solubility in a solvent.
Therefore, the polymer compound represented by the general formula (I) can be used as a photoacid generator for a chemically amplified resist, a resist dissolution inhibitor, or a photocationic polymerization initiator such as an alkyl vinyl ether. is there.

Since the polymer compound of the present invention has a high content of silicon atoms in the molecule, it has excellent resistance to etching by oxygen plasma, and the number of silicon atoms per structural unit (the general formula (I It can be expected that the etching resistance is improved as m) in () is increased. Therefore,
It can also be used as an upper layer of a multilayer resist.

[0020]

The production examples of the compounds of the present invention are described below as working examples. Example 1 In the general formula (I), R ¹ and R ² are ethylene groups, R ³ is a 2-oxocyclohexyl group, Y ⁻ is CF ₃ SO ₃ ⁻ ,
Synthesis of a silicon-containing sulfonium salt in which X is the general formula (III), R ⁴ and R ⁵ are methyl groups, Z is a hydrogen atom, and m is 4: Aren cooling tube, three-way flask for 100 ml with three-way cock Under an atmosphere of argon, 3.51 g of 2,2'-thiodiethanol was dissolved in 50 ml of dry pyridine, and 1,7-dichlorooctamethyltetrasiloxane 10 was added thereto.
ml was gradually added, and the mixture was stirred at room temperature for 1 hour. Then 7
The mixture was stirred for 5 hours while heating in a 0 ° C bath. After completion of the reaction, the reaction mixture was dissolved in dichloromethane, washed with water, and then poured into a large amount of hexane. After removing the supernatant liquid by decantation, the liquid precipitate was dried under reduced pressure overnight to obtain 8.28 g of a polymer compound (yield 83%, weight average molecular weight 27,000 n = 67). Continued 300m
2.1 g of the polymer compound was placed in a 4-neck flask for l,
2-Bromocyclohexanone 0.685 g (0.00
50 ml of a 5 mol) nitromethane solution was added dropwise. 2
After stirring for an hour, silver trifluoromethanesulfonate 1.285
g (0.005 mol) of nitromethane solution 100 ml
Was added dropwise, and stirring was continued for 3 hours. After completion of the reaction, the deposited silver bromide precipitate was filtered off with a glass filter (G4), and the solvent was distilled off under reduced pressure from the filtrate and concentrated to about 50 ml. After pouring this into a large amount of dry ether, the supernatant was removed by decantation, and the residue was dried under reduced pressure overnight to obtain 2.58 g of a silicon-containing sulfonium salt compound.
(Yield 78%) was obtained. 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. Moreover, Shimadzu LC-9A was used for the molecular weight measurement and Shimadzu SPD-6A was used for the detection, and tetrahydrofuran (TH
Showa Denko GPC column (GPC)
KF-80M) was used to determine the polystyrene-reduced molecular weight. ¹ H-NMR (acetone-d ₆ , internal standard substance: tetramethylsilane): δ (ppm) 0.12 (s, 12H), 0.24 (s, 12H),
1.73 to 1.85 (m, 4H) 1.90 to 2.24 (m, 2H), 2.53 to 2.58
(M, 2H), 2.67-2.77 (m, 1H), 3.
04-3.11 (m, 8H), 5.05-5.10.
(M, 1H) IR (KBr tablet): 3040 cm ^-1 (ν _CH ), 1
710 cm ^-1 (ν _{C = O} ), 1264 cm ^-1 (ν _CF ), 1160 cm
^-1 (ν _SO3 ), 1100 cm ^-1 (ν _Si-O-Si ), 103
0 cm ^-1 (ν _SO3 ) Average molecular weight: 31500 Elemental analysis C H S F Si Actual value (% by weight) 35.02 6.03 9.56 8.95 17.33 Theoretical value (% by weight) 34.44 6. 19 9.67 8.61 17.85 (Example 2) In Example 1, 2,2'-thiodiethanol and 1,7 were used.
70% solution of dichlorooctamethyltetrasiloxane
Synthesis was performed in exactly the same manner as in Example 1 except that 0.35 g of imidazole was added immediately before the step of heating to 0 ° C. to obtain a silicon-containing polymer photoacid generator having a weight average molecular weight of 101,000. ¹ H-NMR (acetone-d ₆ , internal standard substance: tetramethylsilane): δ (ppm) 0.12 (s, 12H), 0.24 (s, 12H),
1.73 to 1.85 (m, 4H) 1.90 to 2.24 (m, 2H), 2.53 to 2.58
(M, 2H), 2.67 to 2.77 (m, 1H), 3.
04-3.11 (m, 8H), 5.05-5.10.
(M, 1H) IR (KBr tablet): 3040 cm ^-1 (ν _CH ), 17
10 cm ^-1 (ν _{C = O} ), 1264 cm ^-1 (ν _CF ), 1
160 cm ^-1 (ν _SO3 ), 1100 cm
^-1 (ν _Si-O-Si ), 1030 cm ^-1 (ν _SO3 ) Elemental analysis C H S F Measured value (wt%) 34.88 6.40 9.45 8.25 Theoretical value (wt%) 34. 44 6.19 9.67 8.61 (Example 3) In the same manner as in Example 1, R ¹ and R ² are propylene groups and R
³ is a 2-oxocyclohexyl group, Y ^- is CF ₃ SO ₃
^- , X is the general formula (II), R ⁴ and R ⁵ are methyl groups, Z is a hydrogen atom, and m is 4 to synthesize a silicon-containing sulfonium salt. However, instead of 3.51 g of 2,2'-thioethanol, 3'-thiodipropanol 4.
2 g were used. ¹ H-NMR (acetone-d ₆ , internal standard substance: tetramethylsilane): δ (ppm) 0.12 (s, 12H), 0.24 (s, 12H),
1.73 to 1.85 (m, 8H) 1.90 to 2.24 (m, 2H), 2.53 to 2.58
(M, 2H), 2.67-2.77 (m, 1H), 3.
04-3.13 (m, 8H), 5.05-5.10.
(M, 1H) IR (KBr tablet): 3040 cm ^-1 (ν _CH ), 1
710 cm ^-1 (ν _{C = O} ), 1264 cm ^-1 (ν _CF ),
1160 cm ^-1 (ν _SO3 ), 1100 cm ^-1 (ν
_Si-O-Si ), 1030 cm ^-1 (ν _SO3 ) Average molecular weight: 28500 Elemental analysis C H S F Measured value (wt%) 36.31 6.89 8.95 7.98 Theoretical value (wt%) 36. 73 6.56 9.32 8.31 (Example 4) In the same manner as in Example 1, R ¹ and R ² are ethylene groups and R ^{3 is}
Is a 2-oxocyclohexyl group, Y ^- is CF ₃ S
O ₃ ⁻ and X are the general formula (II), and further R ⁴ and R ⁵
Was synthesized, a silicon-containing sulfonium salt in which Z was a hydrogen atom and m was 1 was synthesized. However, 10 m of 1,7-dichlorooctamethyltetrasiloxane used in Example 1 was used.
3.5 ml of dimethyldichlorosilane was used instead of 1. ¹ H-NMR (acetone-d ₆ , internal standard substance: tetramethylsilane): δ (ppm) 0.25 (s, 6 H), 1.73-1.85 (m, 4
H), 1.90-2.24 (m, 2H), 2.53 ~
2.58 (m, 2H), 2.67-2.77 (m, 1
H), 3.04-3.11 (m, 8H), 5.05-
5.10 (m, 1H) IR (KBr tablet): 3040 cm ^-1 (ν _CH ), 1
710 cm ^-1 (ν _{C = O} ), 1264 cm ^-1 (ν _CF ),
1160 cm ^-1 (ν _SO3 ), 1100 cm ^-1 (ν
_Si-O-Si ), 1030 cm ^-1 (ν _SO3 ) Average molecular weight: 22300 Elemental analysis C H S F Measured value (wt%) 35.54 5.80 14.25 12.91 Theoretical value (wt%) 35. 86 5.29 14.71 13.10 (Example 5) In the same manner as in Example 1, R ¹ and R ² are ethylene groups and R ^{3 is}
Is a 2-oxocyclohexyl group, Y ^- is CF ₃ S
O ₃ ⁻ and X are the general formula (II), and further R ⁴ and R ⁵
Was a t-butyl group, Z was a hydrogen atom, and c was 1, and a silicon-containing sulfonium salt was synthesized. However, 1,7-dichlorooctamethyltetrasiloxane 10 used in Example 1 was used.
6.1 m of di-t-butyldichlorosilane instead of ml
1 was used. ¹ H-NMR (acetone-d ₆ , internal standard substance: tetramethylsilane): δ (ppm) 0.24 (s, 2H), 1.05 to 1.12 (m, 12)
H), 1.53 to 1.58 (m, 2H), 1.73 to
1.85 (m, 2H), 1.90-2.24 (m, 4
H), 2.53-2.58 (m, 2H), 2.67-
2.77 (m, 1H), 3.04 to 3.11 (s, 8)
H), 5.05 to 5.10 (m, 1H) IR (KBr tablet): 3040 cm ^-1 (ν _CH ), 1
710 cm ^-1 (ν _{C = O} ), 1264 cm ^-1 (ν _CF ),
1160 cm ^-1 (ν _SO3 ), 1100 cm ^-1 (ν
_Si-O-Si ), 1030 cm ^-1 (ν _SO3 ) Average molecular weight: 10500 Elemental analysis C H S F Measured value (% by weight) 44.27 6.27 71.52 10.55 Theoretical value (% by weight) 43. 93 6.74 72.33 10.98 (Example 6) In the same manner as in Example 1, R ¹ and R ² are ethylene groups and R ³
Is a 2-oxocyclohexyl group, Y ^- is CF ₃ S
O ₃ ⁻ and X are the general formula (II), and further R ⁴ and R ⁵
Is a methyl group, Z is a trimethylsilyl group, and m is 4. A silicon-containing sulfonium salt was synthesized. However, a polymer compound obtained by the step of dropping 1,7-dichlorooctamethyltetrasiloxane into a pyridine solution of thiodiethanol and then heating (in the general formula (IV), R
¹ , R ² is an ethylene group, X is a general formula (III),
Further, 2 g of a polymer compound in which R ⁴ and R ⁵ are methyl groups, Z is a hydrogen atom, and m is 4 is added to tetrahydrofuran (TH
F) It was dissolved in 20 ml, 0.5 g of hexamethyldisilazane was added thereto, and the mixture was heated at 70 ° C. for 1 hour. This was poured into dry methanol for reprecipitation and endcapping with trimethylsilyl groups. Subsequently, 2 g of the obtained polymer compound was placed in a 4-neck flask for 300 ml, and 0.685 g (0.005 mo) of 2-cyclohexanone bromide was added.
50 ml of a nitromethane solution of 1) was added dropwise. After stirring for 2 hours, 100 ml of a nitromethane solution containing 1.104 g of silver trifluoromethanesulfonate was added dropwise. After further stirring for 1 hour, 100 ml of a nitromethane solution of 2-bromocyclohexanone g was added dropwise, and stirring was continued for 3 hours. After completion of the reaction, the deposited silver bromide precipitate was filtered through a glass filter (G4), and the solvent was distilled off under reduced pressure to about 5
It was concentrated to 0 ml. This was poured into dry ether for reprecipitation. ¹ H-NMR (acetone-d ₆ , internal standard substance: tetramethylsilane): δ (ppm) 0.12 (s, 12H), 0.24 (s, 12H),
1.73 to 1.85 (m, 4H) 1.90 to 2.24 (m, 2H), 2.53 to 2.58
(M, 2H), 2.67 to 2.77 (m, 1H),
3.04 to 3.11 (m, 8H), 5.05 to 5.10.
(M, 1H) IR (KBr tablet): 3040 cm ^-1 (ν _CH ), 1
710 cm ^-1 (ν _{C = O} ), 1264 cm ^-1 (ν _CF ) ,
1160 cm ^-1 (ν _SO3 ), 1100 cm ^-1 (ν
_Si-O-Si ), 1030 cm ^-1 (ν _SO3 ) Average molecular weight: 31500 Elemental analysis C H S F Measured value (wt%) 34.19 6.41 9.25 8.23 Theoretical value (wt%) 34. 44 6.19 9.67 8.61 (Example 7) In the same manner as in Example 1, R ¹ and R ² are ethylene groups and R ^{3 is}
Is a 2-oxopropyl group, Y ⁻ is CF ₃ SO ₃ ^— , X is the general formula (II) , and R ⁴ and R ⁵ are methyl groups,
A silicon-containing sulfonium salt in which Z is a hydrogen atom and m is 4 was synthesized. However, 2-bromocyclohexanone 0.
0.68 g of bromoacetone was used instead of 685 g. ¹ H-NMR (acetone-d ₆ , internal standard substance: tetramethylsilane): δ (ppm) 0.12 (s, 12H), 0.24 (s, 12H),
2.67 to 2.77 (s, 3H), 3.05 to 3.11
(M, 4H), 5.05 to 5.10 (s, 1H) IR (KBr tablet): 3040 cm ^-1 (ν _CH ), 1
710 cm ^-1 (ν _{C = O} ), 1264 cm ^-1 (ν _CF ),
1160 cm ^-1 (ν _SO3 ), 1100 cm ^-1 (ν
_Si-O-Si ), 1030 cm ^-1 (ν _SO3 ) Average molecular weight: 30700 Elemental analysis C H S F Measured value (wt%) 31.56 5.43 9.26 8.32 Theoretical value (wt%) 31. 38 5.69 9.85 8.77 (Example 8) In the same manner as in Example 1, R ¹ and R ² are ethylene groups and R ^{3 is}
Is a 2-oxocyclohexyl group, Y ^- is CF ₃ S
O ₃ ⁻ and X are the general formula (II) , and further R ⁴ and R ⁵
Was synthesized, and a silicon-containing sulfonium salt in which Z is a hydrogen atom and m is 1 was synthesized. However, 6 ml of dichlorodiphenylsilane was used instead of 10 ml of 1,7-dichlorooctamethyltetrasiloxane. ¹ H-NMR (acetone-d ₆ , internal standard substance: tetramethylsilane): δ (ppm) 1.73-1.85 (m, 4H), 1.90-2.24
(M, 2H), 2.53 to 2.58 (m, 2H), 2.
67-2 ,. 7 (m, 1H), 3.04-3.11
(M, 8H), 5.05 to 5.10 (m, 1H), 7.
12-7.73 (m, 10H) IR (KBr tablet): 3040 cm ^-1 (ν _CH ), 1
710 cm ^-1 (ν _{C = O} ), 1570 cm ^-1 (ν _{C = C} ),
1264 cm ^-1 (ν _CF ), 1160 cm
^-1 (ν _SO3 ) , 1100 cm ^-1 (ν _Si-O-Si ), 103
0 cm ^-1 (ν _SO3 ), 900 cm ^-1 (ν _{C = C} ), 675
cm ⁻¹ (ν _{C = C} ), elemental analysis C H S F measured value (wt%) 50.36 9.85 11.68 10.40 theoretical value (wt%) 50.86 9.36 11.95 10. 84 Average molecular weight: 24500 (Example 9) A solution of the compound of Example 1 in acetonitrile (concentration: 32μ)
2 ml of ArF excimer laser (apparatus: HE-460-SM-A manufactured by Lumonix) is irradiated (exposure area: 1 cm ² ), and the exposed area is acetonitrile containing sodium salt of tetrabromophenol blue which is an indicator. 2 ml of the solution was added, and the whole was diluted to 20 ml with acetonitrile, and the visible absorption spectrum of the solution was measured. The amount of acid generated is determined by Analytical Chemistry.
48 (No. 2), 450-451 (1976), according to the method, it calculated | required from the change of the light absorbency of 619 nm. The relationship between the number of moles of the acid and the absorbance was determined by preparing a calibration curve from the absorbance of a known amount of p-toluenesulfonic acid and an acetonitrile solution of the indicator in advance.

From the above measurement method, it was confirmed that 20 nmol of acid was generated when the compound of Example 1 was irradiated with an exposure dose of 80 mJ · cm ⁻² .

[0022]

As described above, the silicon-containing sulfonium salt of the present invention generates an acid with respect to light having a short wavelength of 200 nm or less, and therefore, a photocation which uses light having a short wavelength such as ArF excimer laser. It was found to be useful as a polymerization initiator, a photoresist photosensitizer (photoacid generator), and the like. In particular, since the silicon-containing sulfonium salt of the present invention has a silicon atom in the molecule, it has good oxygen plasma resistance and is useful for photoresists.

Claims (2)

(57) [Claims] 1. A silicon-containing sulfonium salt compound represented by the following general formula (I): Embedded image (N is a positive integer of 1 to 300, Y ⁻ is a counter anion, Z is a hydrogen atom or a trimethylsilyl group, and R ¹ and R ² are carbon.
A linear, branched or cyclic alkylene group having a prime number of 2 to 10 , R ³ is a linear, branched or cyclic 2-oxoalkyl group having a carbon number of 3 to 7, and X is a general formula (II) or (III ) Is shown. ) [Chemical 2] (M is a positive integer of 1 to 100, R ⁴ and R ⁵ are carbon atoms 1 to
8 is a linear, branched or cyclic alkyl group or phenyl group. ) 2. The counter anion represented by Y is BF ₄
AsF ₆ ￣, SbF ₆ ￣, PF ₆ ￣, or CF ₃ SO
_3. The silicon-containing sulfonium salt according to claim 1, which is ₃ ft.