JPH08190204A - Photosensitive composition for silylation and method for forming fine pattern - Google Patents

Abstract

(57) [Summary] [Object] To provide a photosensitive composition for silylation excellent in oxygen plasma resistance and a fine pattern forming method. [Structure] After a resist film 2 containing a photobase generator is formed, it is exposed to an excimer laser beam 4 to form a base generation region 2A. Next, after being treated with the silylation vapor 5 to form the silylation region 2B, it is etched with oxygen plasma.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photolithography step in a semiconductor device manufacturing process, and more particularly to a photosensitive composition used in a silylation method and a fine pattern forming method using the photosensitive composition (hereinafter referred to as resist). .

[0002]

2. Description of the Related Art In recent years, in the field of various electronic devices that require microfabrication such as semiconductor devices, demands for higher density and higher integration of devices have been more and more increased. It is becoming essential to make the pattern finer. And in the semiconductor device manufacturing process,
The photolithography process plays an important role in forming a fine pattern. Furthermore, in the photolithography process, with the miniaturization of semiconductor devices,
A method of accurately transferring a resist pattern to a substrate is required, and dry etching using gas plasma or the like is being used instead of conventional wet etching. In particular, as a method of transferring a resist pattern using oxygen plasma, a single-layer silylation method in which a silicon compound having high oxygen plasma resistance is selectively introduced onto the surface of a resist film has been actively studied.

In the conventional single-layer silylation method, after the pattern exposure, the resist film surface in the light-irradiated portion or the non-irradiated portion is selectively silylated, and then dry development is performed by oxygen plasma for patterning. Examples of the method for selectively silylating the exposed portion include, for example, Journal of Vacuum Science and Technology (J
individual of Vacuum Science
& Technology) B, Volume 9, No. 6, pp. 3399-3405 (1991).
o Baik's DESIRE (Diffusion
Enhanced Silation Resis
t) There is a process. In the DESIRE process, after pattern exposure and baking, the resist film is subjected to silylation using a silylating agent (eg, hexamethyldisilazane), and then dry development is performed with oxygen plasma to form a pattern. . At this time, the hydroxy group (—OH group) of the resin (for example, novolac resin) and the silylating agent react with each other by silylation in the exposed portion to form a silyl ether [—OSi (CH ₃ ) ₃ ]. The etching resistance to oxygen plasma is improved. On the other hand, in the non-exposed area, the photosensitive agent (for example,
A silylation reaction does not occur because a crosslinking reaction occurs between the resin and a naphthoquinonediazide group-containing photosensitizer. As a result, a difference in etching rate due to oxygen plasma occurs between the exposed portion and the unexposed portion, and a negative pattern can be formed.

Further, as a method for selectively silylating the unexposed area, for example, a resist comprising a resin, a photoacid generator, and a crosslinking agent which causes a crosslinking reaction with the resin by the action of an acid is used. JP-A-4-28704
There is the method of Fujino et al. In this method, the pattern exposure, baking, silylation, and dry development with oxygen plasma are the same as the above-described method and step, but in this method, the exposed part is crosslinked with the resin by the action of the acid generated by the exposure. Because the agent causes a crosslinking reaction,
The silylating agent cannot diffuse into the resist film and the silylation reaction does not occur. On the other hand, in the unexposed area, since such a crosslinking reaction does not occur, it is silylated. As a result, a difference in etching rate occurs between the exposed portion and the unexposed portion, and a positive pattern can be formed.

[0005]

However, the resist used in the conventional single-layer silylation method has only one hydroxyl group capable of reacting with a silylating agent per unit of resin (for example, novolac resin or polyvinylphenol). Absent. Therefore, the concentration of silyl groups introduced into the resist is low, and the etching resistance to oxygen plasma is not sufficient. Further, in the conventional single-layer silylation method, the silylation reaction proceeds even in a region where it is not desired to actually silylate, so that the contrast of silylation is lowered. Further, in the conventional single-layer silylation method, silylating agents currently used for silylation include hexamethyldisilazane, dimethylsilyldimethylsilane, tetramethyldisilazane, N, N-dimethylaminotrimethylsilane, 1, 1, 3, 3, 5, 5-
Only a compound such as hexamethylcyclotrisilazane that can introduce only one silicon atom into one hydroxyl group of a resin (for example, novolac resin or polyvinylphenol) by silylation.

Therefore, the concentration of silicon atoms introduced into the resist is low, and the etching resistance to oxygen plasma is not sufficient. As a result, the shape of the fine pattern is particularly deteriorated after the etching with oxygen plasma, which makes it difficult to control the dimension of the resist pattern. From this,
In the silylation method of a single-layer resist, there is a demand for a method of forming a silylation region with higher concentration and high selectivity to improve the etching resistance of the silylation layer and the silylation contrast. Therefore, the technical problem in this field is the development of a photosensitive composition which can be silylated with high concentration and high selectivity, and a method thereof.

It is an object of the present invention to provide a photosensitive composition having a higher concentration of introduced silicon atoms, excellent in oxygen plasma resistance and capable of highly selective silylation, and a fine pattern forming method.

[0008]

Means for Solving the Problems As a result of earnest research by the present inventor, as a result of the above-mentioned problems, the above-mentioned problem is that a resist for silylation is coated on a substrate to be processed, pre-baked and then exposed, and then a silylating agent is used. In the method for forming a fine pattern in which a silylation region is formed by performing silylation in a liquid phase or a gas phase and the resist layer is etched by gas plasma using the silylation region as a mask, a compound that promotes silylation in the resist Or a polyfunctional silylating agent is used as the silylating agent, or a silylating agent having a plurality of silicon atoms in the molecule is used as the silylating agent. The present invention has been found to be solved.

The compound having two or more hydroxy groups in the molecule used in the present invention includes 2,2'-dihydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4'-dihydroxybenzophenone, 2,
3,4-trihydroxybenzophenone, 2,3,4 '
-Trihydroxybenzophenone, 2,2 ', 4,4'
-Tetrahydroxybenzophenone, 2 ', 4'-dihydroxyacetophenone, 2', 5'-dihydroxyacetophenone, 2 ', 6'-dihydroxyacetophenone, 3', 5'-dihydroxyacetophenone, 2 ',
Examples thereof include 3,4′-trihydroxyacetophenone, catechol, 1,2,4-benzenetriol, but not limited to these examples. These compounds are, for example, 2,2 ′, as shown in FIG.
The hydroxy group in the molecule of 4,4 ', tetrahydroxybenzophenone reacts with dimethylsilyldimethylamine as a silylating agent. Therefore, the concentration of the silyl group introduced into the resist is increased as compared with the photosensitive composition containing no such compound, and as a result, the etching resistance is improved.

As the photobase generator used in the present invention, for example, a compound represented by the following general formula (1) is used.

[0011]

(Wherein R ¹ represents hydrogen or a nitro group, R ² represents a hydrogen or aryl group, R ³ and R ⁴ represent a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms.

The photobase generator represented by the general formula (1) is
For example, Journal of the American Chemicals
Society (Journal of the Ame)
rican Chemical Society) 11
It is synthesized according to the method of James et al. Described in Volume 3, 4304-4313 (1991). The photobase generator that can be used in the present invention,
[[(2-Nitrobenzyl) oxy] carbonyl] cyclohexylamine, [[(2,6-dinitrobenzyl) oxy] carbonyl] cyclohexylamine, N-[[(2
-Nitrophenyl) -1-methylmethoxy] carbonyl] cyclohexylamine, N-[[(2,6-dinitrophenyl) -1-methylmethoxy] carbonyl] cyclohexylamine, N-[[(2-nitrophenyl) -1 −
(2'-Nitrophenyl) methoxy] carbonyl] cyclohexylamine, N-[[(2,6-dinitrophenyl) -1- (2'6'-dinitrophenyl) methoxy]
Carbonyl] cyclohexylamine and the like, but are not limited to these examples. The amines generated from these photobase generators have a function of promoting the reaction between the hydroxyl group of the resin and the silylating agent when the resist is treated with the silylating agent. Therefore, in the exposed area, silylation is promoted more, the silylation contrast is improved, and a finer pattern can be formed than in the photosensitive composition containing no photobase generator.

Then, a compound having two or more hydroxyl groups in the molecule and / or a resist material for silylating only a photobase generator with a photobase generator, for example, a novolak type resist (a novolak resin + a photosensitizer having a quinonediazide group). Agent + solvent) and 0.1 to resin respectively
10% by weight (more preferably 0.5 to 7% by weight), 1 to
The photosensitive composition (resist) of the present invention is adjusted by adding 40% by weight (more preferably 5 to 30% by weight). The photosensitive composition thus obtained is spin-coated on a substrate to be processed, exposed, baked, and then silylated in a gas phase or in a liquid phase using a silylating agent to selectively expose only the exposed portion. Silylation.

Further, a compound having two or more hydroxyl groups in the molecule can be silylated only in the unexposed area because a crosslinking reaction occurs in the exposed area, such as polyvinylphenol (hereinafter referred to as PVP) and a solvent. 1 to 40% by weight relative to PVP (more preferably 5%
(About 30% by weight), the photosensitive composition (resist) of the present invention is prepared. The photosensitive composition thus obtained is spin-coated on a substrate to be processed, and after exposure,
Silylation is performed in a gas phase or a liquid phase by using a silylating agent, and only the unexposed portion is selectively silylated.

As the silylating agent used for the silylation at this time, an organic compound containing Si can be used. For example, in the case of gas phase silylation, hexamethyldisilazane, dimethylsilyldimethylamine, tetramethyldisilazane, N, N
-Dimethylaminotrimethylsilane and the like can be used. In the case of liquid phase silylation, bis (dimethylamino) methylsilane, bis (dimethylamino) dimethylsilane, 1,
1,3,3,5,5-hexamethylcyclotrisilazane or the like can be used.

Next, the silylated resist film is etched by oxygen plasma. As a result, it was confirmed that the silylated layer has excellent etching resistance and a good pattern shape, as compared with a compound having two or more hydroxyl groups in the molecule and / or a compound not containing a photobase generator. did. Therefore, the photosensitive composition (resist) of the present invention containing a compound having two or more hydroxyl groups in the molecule and / or a photobase generator is effective as a photosensitive composition for silylation.

In addition, after performing the step of exposing the resist film to water vapor, a silylation method in which the resist film is treated with a polyfunctional silylating agent, or the resist film is treated with a polyfunctional silylating agent (eg Si (NR ) _X : x ≧ 2), and then further treated with a silanol compound, the polyfunctional silating agent and silanol compound used in the silylation method include bis (dimethylamino) methylsilane and bis (dimethylamino) dimethyl. Silane, bis (diethylamino)
Dimethylsilane, methyltris (dimethylamino) silane, trimethylsilanol, triethylsilanol and the like can be used. Then, in the silylation method in which the resist film is treated with a polyfunctional silylating agent, as shown in FIG. 5, after the resin (paravinylphenol) and the silylating agent are reacted, water (H 2 ₂ O) and further with a silylating agent, and as a result, a plurality of silicon atoms are introduced per unit of resin, the concentration of silyl groups introduced into the resist increases, and As a result, etching resistance is improved. Further, in the silylation method in which the resist is treated with a polyfunctional silylating agent and then further treated with a silanol compound, as shown in FIG. 6, after the reaction between the resin and the silylating agent, the reaction with the silanol compound is further conducted. Due to
Since two silicon atoms are introduced per resin unit, the concentration of silyl groups introduced into the resist is increased, and as a result, etching resistance is improved.

Then, the silylated resist film is etched by oxygen plasma. As a result, after performing the step of exposing the resist film to water vapor, a silylation method of treating the resist film with a polyfunctional silylating agent, or after treating the resist film with a polyfunctional silylating agent, The method of silylating a resist film treated with a silanol compound is superior in the etching resistance of the silylated layer to the conventional method of treating the resist film only once with a silylating agent.
It was also confirmed that the pattern shape was good. From this, after performing a step of exposing the resist film to water vapor, a silylation method in which the resist film is treated with a polyfunctional silylating agent, or after treating the resist with a polyfunctional silylating agent, a silanol compound is further added. The silylation method of the resist film treated with is effective as a silylation method of the resist film in the fine pattern forming method.

As the silylating agent having a plurality of silicon atoms in the molecule as the silylating agent used in the present invention, for example, the silylating agent represented by the general formula (2) is used.

[0021]

(However, Me represents a methyl group, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a methyl group or an ethyl group.) The silylating agent represented by the general formula (2) is, for example, as follows. Be synthesized. That is, it is synthesized by reacting the silicon compound represented by the general formula (3) with an equimolar amount of the silanol compound represented by the general formula (4) in the absence of a solvent at room temperature or under heating.

[0023]

(However, R ¹ represents a hydrogen atom or a methyl group.)

[0025]

(However, R ² represents a methyl group or an ethyl group.) Examples of the silylating agent having a plurality of silicon atoms in the molecule usable in the present invention include 1-dimethylamino-1,3,3,3.
-Tetramethyldisiloxane, 1-dimethylamino-
1,1,3,3,3-pentamethyldisiloxane, 1-
Examples thereof include dimethylamino-1-methyl-3,3,3-triethyldisiloxane and 1-dimethylamino-1,1-dimethyl-3,3,3-tetraethyldisiloxane, but are not limited to these examples. Not a thing.

The silylated layer formed by silylation using a silylating agent having a plurality of silicon atoms in the molecule is formed by a conventional silylating agent having only one silicon atom in the molecule. It was confirmed that the etching resistance was better and the pattern shape was better than that of the silylated layer. Therefore, the silylation method using a silylating agent having a plurality of silicon atoms in the molecule is effective for forming a fine pattern.

[0028]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

(Embodiment 1) FIGS. 1A to 1D are sectional views of a semiconductor chip for explaining an embodiment 1 of the present invention. First, novolac resin (m-cresol novolac,
20 g of weight average molecular weight MW = 6500), 4 g of 1,2-naphthoquinonediazide-4-sulfonic acid ester, and 1 g of [[(2,6-dinitrobenzyl) oxy] carbonyl] cyclohexylamine as a photobase generator in 75 g of ethyl lactate. It was dissolved and filtered through a 0.2 μm pore membrane filter to prepare a resist solution. As shown in FIG. 1A, the obtained solution was spin-coated on a silicon substrate 1 and baked on a hot plate at 90 ° C. for 60 seconds to form a resist film 2 having a thickness of 1.0 μm.

Next, as shown in FIG. 1 (b), a KrF excimer laser is used as an exposure light source on the resist film 2 for Kr.
Exposure was performed with a laser beam 4 using an F excimer stepper (numerical aperture = 0.50). This exposure forms the base generation region 2A. Next, as shown in FIG.
The resist was exposed to dimethylsilyldimethylamine vapor 5 having a pressure of 20 Torr for 1 minute while baking the resist film at 100 ° C., and the resist in the exposed region was silylated to form a silylated region 2B.

Next, as shown in FIG. 1D, an electron cycloton resonance etching method (O ₂ -ECR) using oxygen is used, Power = 50 W, pressure = 5 mTorr, temperature =
Silylation region 2B under conditions of -50 ° C and time = 90 seconds
As a result of etching using as a mask, 0.22 μm
An L / S (line and space) rectangular pattern was obtained.

Although [[(2,6-dinitrobenzyl) oxy] carbonyl] cyclohexylamine was used as the photobase generator in Example 1 above, N-[[(2,6
Even if -dinitrophenyl) -1-methylmethoxy] carbonyl] cyclohexylamine is used, the same effect as in the above-described example can be obtained.

(Example 2) In the same manner as in Example 1, a resist film 2 is formed on a silicon substrate, and exposure and baking are performed. Next, expose the exposed resist film to bis (dimethylamino)
Dimethylsilane 10%, xylene 87%, N-methyl-
The exposed area was selectively silylated by immersing the resist film in a mixed solution containing 3% of 2-pyrrolidone at room temperature for 90 seconds, and then rinsing the resist film with xylene. Then O ₂
As a result of etching by −ECR (Powur = 50 W, pressure 5 mTorr, temperature = −50 ° C., time = 90 seconds), a rectangular pattern of 0.22 μmL / S was obtained.

(Comparative Example 1) As Comparative Example 1, a resist solution containing no [[(2,6-dinitrobenzyl) oxy] carbonyl] cyclohexylamine as a photobase generator in Example 1 was prepared. A resist pattern was formed in the same manner as in 1. As a result, 0.25 μm
Only L / S was resolved.

Example 3 20 g of novolak resin (m-cresol novolac, MW = 6500), 4 g of 1,2-naphthoquinonediazide-4-sulfonic acid ester,
[[(2,6-Dinitrobenzyl) oxy] carbonyl] cyclohexylamine 1 g, 2,2 ′, 4,4′-tetrahydroxybenzophenone 4 g as a compound having two or more hydroxy groups in the molecule, and ethyl lactate 71 g
And then filtered through a 0.2 μm pore membrane filter to prepare a resist solution. The obtained solution was spin-coated on a silicon substrate in the same manner as in Example 1 and baked on a hot plate at 90 ° C. for 60 seconds to give a thickness of 1.0 μm.
Was formed.

The film thus formed was exposed using a KrF excimer stepper (numerical aperture = 0.50) with a KrF excimer laser as an exposure light source. 17 after exposure
The resist in the exposed region was silylated by baking at 0 ° C. for 2 minutes and then exposing the resist film to 100 ° C. while exposing it to dimethylsilyldimethylamine vapor having a pressure of 20 Torr for 1 minute. After that, O ₂ -ECR (Power = 5
0 W, pressure = 5 mTorr, temperature = −50 ° C., time = 9
As a result of etching for 0 seconds, 0.20 μmL
A rectangular pattern of / S was obtained.

In the above Example 3, 2,2 ', 4,4' was added to the compound having two or more hydroxy groups in the molecule.
-Tetrahydroxybenzophenone was used,
The same effect can be obtained by using 3,4-trihydroxybenzophenone.

(Example 4) In the same manner as in Example 3, a resist film is formed, exposed and baked. Next, the exposed resist film is treated with bis (dimethylamino) dimethylsilane 10
%, Xylene 87%, N-methyl-2-pyrrolidone 3%
The exposed area was selectively silylated by immersing the resist solution in a room temperature for 90 seconds and then rinsing the resist film with xylene. After that, O ₂ -ECR (Power
As a result of etching with r = 50 W, pressure = 5 mTorr, temperature = −50 ° C., time = 90 seconds, 0.20
A rectangular pattern of μmL / S was obtained.

(Example 5) Polyvinylphenol (MW
= 34000) 20 g, 5 g of 2,2 ′, 4,4′-tetrahydroxybenzophenone as a compound having two or more hydroxy groups in the molecule is dissolved in 75 g of ethyl lactate, and filtered with a 0.2 μm pore membrane filter. A resist solution was prepared. The obtained solution is spin-coated on a silicon substrate and then placed on a hot plate at 100 ° C for 6 minutes.
Baking was performed for 0 second to form a resist film having a thickness of 0.7 μm. The thus-formed film was exposed to dimethylsilyldimethylamine vapor having a pressure of 10 Torr for 1 minute while being heated to 100 ° C. to silylate the resist film on the entire surface.

After that, O ₂ -ECR (Power = 50
Etching was performed at W, pressure = 5 mTorr, temperature = −50 ° C.). As a result, it took 600 seconds to completely etch the resist film. As a comparative example, 2,
A resist solution containing no 2 ', 4,4'-tetrahydroxybenzophenone was prepared, and film formation and etching were performed under the same conditions. As a result, the time required to completely etch the resist film was 400 seconds. From this, it was revealed that the photosensitive composition (resist) of the present Example 5 had excellent resistance to oxygen plasma.

The same effect was obtained by using 2,3,4'-trihydroxybenzophenone as the compound having two or more hydroxy groups in the molecule.

(Sixth Embodiment) FIGS. 2A to 2D are sectional views of a semiconductor chip for explaining a sixth embodiment of the present invention. First, polyvinylphenol (MW = 34000)
20 g, 2,2 ', 4,4'-tetrahydroxybenzophenone (5 g) was dissolved in 75 g of ethyl lactate, and the amount was adjusted to 0.
A resist solution was prepared by filtering with a 2 μm pore membrane filter. The obtained solution is as shown in FIG.
Spin coating on silicon substrate 1 and 1 on hot plate
The resist film 12 having a thickness of 0.7 μm was formed by baking at 00 ° C. for 60 seconds.

Next, as shown in FIG. 2B, contact exposure is performed on the resist film 12 using an ArF excimer laser as an exposure light source to form a resin cross-linking region 12A in the exposed portion.
Next, as shown in FIG. 2C, the resist film is exposed to dimethylsilyldimethylamine vapor having a pressure of 10 Torr for 1 minute while being heated to 100 ° C., and the silylated region 12B is formed on the surface of the resist film 12 in the unexposed region. Was formed. Next, as shown in FIG. 2D, O ₂ -ECR (Power =
50 W, pressure = 5 mTorr, temperature-50 ° C., time = 9
As a result of etching for 0 seconds, 0.18 μmL
A rectangular pattern of / S was obtained.

(Embodiment 7) A resist film 12 was formed and contact exposure was carried out in the same manner as in Embodiment 6, and then the resist film 12 was formed with bis (dimethylamino) dimethylsilane 10% and xylene 8.
The unexposed region was selectively silylated by immersing the resist film in a mixed solution of 7% and 3% N-methylpyrrolidone for 90 seconds at room temperature, and then rinsing the resist film with xylene. Then, etching was performed by O ₂ -ECR (Power = 50 W, pressure = 5 mTorr, temperature = −50 ° C., time = 90 seconds), and as a result, a rectangular pattern of 0.19 μmL / S was obtained.

Comparative Example 2 As Comparative Example 2, a resist solution containing no 2,2 ′, 4,4′-tetrahydroxybenzophenone in Example 6 was prepared and a resist pattern was formed in the same manner as in Example 6. did. as a result,
Only 0.23 μmL / S was resolved.

(Example 8) Polyvinylphenol (MW
= 34000) was dissolved in 80 g of ethyl lactate, and filtered through a 0.2 μm-pore membrane filter to prepare a resist solution. The obtained solution was spin-coated on a silicon substrate and baked on a hot plate at 100 ° C. for 60 seconds to form a resist film having a thickness of 0.7 μm. Next, the resist film is exposed to water vapor for 30 seconds, and then bis (dimethylamino) dimethylsilane 1 is used as a polyfunctional silylating agent.
The resist film was silylated by immersing it in a mixed solution of 0%, xylene 87%, and N-methylpyrrolidone 3% at room temperature for 90 seconds, and then rinsing the resist film with xylene. After that, O ₂ -ECR (Power = 50
Etching was performed at W, pressure = 5 mTorr, temperature = −50 ° C.). As a result, it took 530 seconds to completely etch the resist film. As shown in Example 5, when the steam treatment was not performed, the time required for etching was 400 seconds. Therefore, the photosensitive composition (resist) of Example 8 has excellent resistance to oxygen plasma. It became clear.

Example 9 By the same method as in Example 8, a resist film having a thickness of 0.7 μm was formed. Then, an ArF excimer laser is used as an exposure light source on the created resist film,
Contact exposure was performed. Next, expose the resist film to water vapor for 30 seconds,
Then bis (dimethylamino) dimethylsilane 10%,
The resist film was silylated by immersing it in a mixed solution of 87% xylene and 3% N-methylpyrrolidone at room temperature for 90 seconds, and then rinsing the resist film with xylene. Then, etching was performed by O ₂ -ECR (Power = 50 W, pressure = 5 mTorr, temperature = −50 ° C.). As a result, a rectangular pattern of 0.19 μmL / S was obtained.

(Example 10) In the same manner as in Example 8,
A resist film having a thickness of 0.7 μm was formed. Next, the resist film is immersed in a mixed solution of 10% bis (dimethylamino) dimethylsilane, 87% xylene and 3% N-methylpyrrolidone at room temperature for 90 seconds, and then the resist film is rinsed with xylene, and then trimethylsilanol is added. 20
%, N-methylpyrrolidone 4%, and xylene 76% were immersed in a mixed solution at room temperature for 60 seconds and rinsed with xylene to silylate the resist film. After that, O ₂ -E
Etching was performed by CR (Power = 50 W, pressure = 5 mTorr, temperature = −50 ° C.). As a result, it took 500 seconds to completely etch the resist film.
As shown in Example 5, when the silanol compound was not treated, the time required for etching was 400 seconds. Therefore, the photosensitive composition (resist) of Example 10 was used.
Have been found to have excellent resistance to oxygen plasma.

(Synthesis Example 1) 1-dimethylamino-1,
Synthesis of 3,3,3-tetramethyldisiloxane was performed as follows.

10 equipped with a thermometer, dropping funnel and reflux tube
To a 0 ml three-necked flask, 25 g (0.19 mol) of bis (dimethylamino) methylsilane was added and ice-cooled. 17 g (0.19 mol) of trimethylsilanol was slowly added thereto dropwise from a dropping funnel. After completion of dropping, the mixture was reacted for 1 hour in an ice water bath. Then, the mixture was distilled under reduced pressure to obtain 16.7 g (yield 50%) of 1-dimethylamino-1,3,3,3-tetramethyldisiloxane. The bp of this substance is 34-35 ° C (25 mmH
g), IR (cm ^-1 ) is 2950 (νC-H), 215
0 (νSi-H), 1060 (νSi-O-Si), 1
It was 255 (νSi-Me).

Example 11 Polyvinylphenol (M
W-34000) 20 g is dissolved in ethyl lactate 85 g,
Further, it was filtered with a 0.2 μm pore membrane filter to prepare a resist solution. The obtained solution was spin-coated on a silicon substrate, and baked on a hot plate at 100 ° C. for 60 seconds to form a 0.7 μm-thick resist film.
The FTIR spectrum of the resist film thus prepared was measured. Next, a resist film was obtained from Synthesis Example 1
The entire surface of the film was immersed in a mixed solution of 10% dimethylamino-1,3,3,3-tetramethyldisiloxane, 87% xylene and 3% N-methylpyrrolidone at room temperature for 120 seconds, and then rinsed with xylene. Silylated. Then, the FTIR spectrum after silylation was measured. The FTIR difference spectrum at that time is shown in FIG. FIG.
From the Si-O-Si bond after silylation
The absorption at 68 cm ^-1 was increased. From this result, 1-
In the silylation using dimethylamino-1,3,3,3-tetramethyldisiloxane, it became clear that a plurality of silicon atoms were introduced to one hydroxyl group of the resin (polyvinylphenol). It was

Comparative Example 3 As Comparative Example 3, Example 11 was used.
However, the silylation of the resist film was performed by heating at 100 ° C. and exposing it to 10 Torr of dimethylsilyldimethylamine vapor for 2 minutes. As a result, in the FTIR difference spectrum, there was no absorption derived from the Si-O-Si bond. From this, it was clear that in the silylation using dimethylsilyldimethylamine, only one silicon atom was introduced into one hydroxyl group of the resin.

(Embodiment 12) In the same manner as in Embodiment 11,
The resist film was silylated. Next, Rutherford backscattering analysis (hereinafter abbreviated as RBS) was performed using a backscattering measurement device AN-2500 (incident ion: ⁴ He ⁺ , incident energy: 2 MeV, beam current: 1 nA) manufactured by Nisshin High Voltage Co., Ltd. Then, the Si concentration of the silylated layer was measured. Table 1 shows the results.

(Comparative Example 4) As Comparative Example 4, RBS of a resist film which was silylated by exposing it to 10 Torr of dimethylsilyldimethylamine vapor for 2 minutes while heating the resist film to 100 ° C was also performed. Table 1 shows the results.

[0055]

[Table 1]

From these results, 1-dimethylamino-
In the silylation using 1,3,3,3-tetramethyldisiloxane, it was revealed that the Si concentration in the silylated region was higher than that in the conventional method.

(Example 13) Polyvinylphenol (M
W = 34000) 20 g dissolved in 85 g ethyl lactate,
Further, it was filtered with a 0.2 μm pore membrane filter to prepare a resist solution. The obtained solution was spin-coated on a silicon substrate, and baked on a hot plate at 100 ° C. for 60 seconds to form a 0.7 μm-thick resist film.
The film thus formed was subjected to contact exposure using an ArF excimer laser as an exposure light source. After exposure, the resist film,
Immerse in a mixed solution of 10% 1-dimethylamino-1,3,3,3-tetramethyldisiloxane, 87% xylene and 3% N-methylpyrrolidone at room temperature for 120 seconds,
Then, the resist film was rinsed with xylene, and the resist in the unexposed area was silylated. After that, O ₂ -ECR (Po
wer = 50 W, pressure = 5 mTorr, temperature = −50
As a result of etching at 90 ° C. for 90 seconds,
A rectangular pattern of 0.18 μmL / S was obtained.

[0058]

As described above, the photosensitive composition of the present invention containing a compound having two or more hydroxyl groups in the molecule and / or a photobase generator is a silylated layer after silylation. It has excellent resistance to oxygen plasma and fine pattern forming ability and is effective as a photosensitive composition for silylation. Further, after performing the step of exposing the resist film to water vapor, a silylation method in which the resist film is treated with a polyfunctional silylating agent, or after the resist film is treated with a polyfunctional silylating agent, a silanol compound is further added. The silylation method of treating with or a silylation method using a silylating agent having a plurality of silicon atoms in the molecule is excellent in oxygen plasma resistance of the silylated layer after silylation, and is a method for forming a fine pattern of a resist film. Is effective as.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor chip for explaining a first embodiment of the present invention.

FIG. 2 is a sectional view of a semiconductor chip for explaining a sixth embodiment of the present invention.

FIG. 3 is an FT of a resist film in Example 11 of the present invention.
The figure which shows IR difference spectrum.

FIG. 4 is a diagram showing a reaction between a compound having two or more hydroxyl groups in a molecule used in Examples and a silylating agent.

FIG. 5 is a diagram showing a reaction between a resin and a silylating agent in a silylation method in which a resist film is exposed to water vapor and then treated with a polyfunctional silylating agent.

FIG. 6 is a diagram showing a reaction between a resin, a silylating agent, and a silanol compound in a silylation method in which a resist film is treated with a polyfunctional silylating agent and then further treated with a silanol compound.

[Explanation of symbols]

 1 Silicon Substrate 2, 12 Resist Film 2A Base Generation Area 2B, 12B Silylation Area 3 Mask 4 KrF Excimer Laser Light 5 Silylation Vapor 12A Resin Crosslinking Area

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01L 21/027 21/3065 H01L 21/302 H

Claims (9)

[Claims] 1. A photosensitive composition for silylation is coated on a substrate to be processed, pre-baked and exposed, and then silylation is performed in a liquid phase or a gas phase using a silylating agent to form a silylated region. In the method for forming a fine pattern in which the photosensitive composition layer is formed by etching, and the photosensitive composition layer is etched by gas plasma using the silylation region as a mask, the photosensitive composition contains a compound that promotes silylation, or A method for forming a fine pattern, wherein a polyfunctional silylating agent is used as an agent, or a silylating agent having a plurality of silicon atoms in a molecule is used as the silylating agent. 2. The fine pattern forming method according to claim 1, wherein the compound that promotes silylation is a compound having two or more hydroxyl groups in the molecule. 3. A photosensitive composition for silylation, which comprises a compound that promotes silylation and has a compound having two or more hydroxy groups in the molecule. 4. The fine pattern forming method according to claim 1, wherein the compound that promotes silylation is a photobase generator that generates a base upon exposure. 5. The method for forming a fine pattern according to claim 1, wherein the compound that promotes silylation is a photobase generator which is represented by the general formula (1) and generates a base upon exposure. (However, R ¹ is hydrogen or nitro group, R ² is hydrogen or aryl group, R ³ and R ⁴ are linear or branched having 1 to 6 carbon atoms,
Alternatively, it represents a cyclic alkyl group. ) 6. A photosensitive composition for silylation, which comprises a compound which promotes silylation and which generates a base upon exposure. 7. The fine pattern formation according to claim 1, wherein the step of silylating includes a step of exposing the photosensitive composition layer to water vapor and a step of treating the photosensitive composition layer with a polyfunctional silylating agent. Method. 8. The silylation step comprises the steps of treating the photosensitive composition layer with a polyfunctional silylating agent, and treating the photosensitive composition layer with a silanol compound.
The method for forming a fine pattern described. 9. The fine pattern forming method according to claim 1, wherein the silylating agent having a plurality of silicon atoms in the molecule is a silylating agent represented by the general formula (2). (However, Me represents a methyl group, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a methyl group or an ethyl group.)