JPH06123972A - Positive resist material - Google Patents

Abstract

PURPOSE:To provide a positive resist material for a high energy ray having high sensitivity, high resolution and excellent process adaptability which has not been realized in conventional materials. CONSTITUTION:This positive resist material contains poly(hydroxystyrene) resin (a) in which t-butoxycarbonyl group is substituted for hydrogen atoms in a part of hydroxyl groups, dissolution preventing agent (b), and onium salt (c) with weight proportion of 0.55<=a, 0.07<=0.40 and 0.005<=c<=0.15 satisfying a+b+c=1. This resist material can be developed with an alkali aq. soln. and reacts to high energy rays. The dissolution preventing agent (b) has one or more t-butoxycarbonyloxy groups in one molecule. The onium salt (c) is expressed by general formula (R)nAM, wherein R is an aromatic or substd. aromatic group, and each R may be the same or different, A is sulfonium or iodonium, M is xylate group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive resist material, and in particular, it has a high sensitivity to high-energy rays such as deep ultraviolet rays, electron beams and X-rays, and can be developed with an alkaline aqueous solution. The present invention relates to a positive resist material suitable for processing.

[0002]

2. Description of the Related Art Conventionally, with the high integration and high speed of LSIs (high-density integrated circuits), miniaturization of pattern rules has been demanded, but light emitted from a light source used in a normal optical exposure technique is required. Has a long wavelength and is not a single wavelength, so there is a limit to the miniaturization of the pattern rule. Therefore, g-rays (wavelength 436 nm) or i-rays (wavelength 365 nm) emitted from an ultra-high pressure mercury lamp are also used as a light source.

However, even in this case, about 0.5 μ
The pattern rule of the resolution of m is the limit, and the LSI that can be manufactured is only the degree of integration of about 16 Mbit DRAM. Therefore, in recent years, far-ultraviolet lithography, which uses far-ultraviolet rays as a light source and has a shorter wavelength than g-line and i-line, is regarded as promising.

According to deep ultraviolet lithography, it is 0.1
It is also possible to form a pattern rule of up to 0.3 μm, and when a resist material having low light absorption is used,
It is possible to form a pattern having a side wall that is nearly vertical to the substrate, and it is also possible to transfer the pattern at once, so that the pattern formation processing efficiency (throughput) is higher than that of lithography using an electron beam. Excellent in high points. Moreover, in recent years, high-intensity K
Since the use of the rF excimer laser has become possible, it is necessary to use a highly sensitive resist material from the viewpoint of mass-producing LSI using the light source.

Therefore, in recent years, a chemically amplified resist material has been developed which has sensitivity equal to or higher than that of the conventional high-sensitivity resist material, and has high resolution and high dry etching resistance and which is produced by using an acid as a catalyst (for example, Ryu). (Liu)
Et al., Journal of Vacuum Science and Technology (J. Vac. Techno.), Volume B6, page 379, 1988, Already Shipley (S.
hipley) has commercialized a chemically amplified negative resist material (SAL601ER7: trade name of Shipley), which is composed of three components of a novolac resin, a melamine compound and an acid generator.

However, when a negative resist material is used in the LSI manufacturing process, it is easy to form wirings and gate portions, but it is difficult to form contact holes that require fine processing. There was a drawback that was. In addition, when patterning is performed with deep ultraviolet rays, electron beams or X-rays using the conventionally proposed chemically amplified positive type resist material as it is,
Since the solubility of the resist surface decreases and the pattern after development tends to overhang, it becomes difficult to control the size of the pattern, and the dimensional controllability during substrate processing using dry etching is improved. It had the drawback of not only damaging it but also causing the collapse of the putter [K. G. Chion et al., Journal of Vacuum Science and Technology, B7].
Vol., (6), p. 1771, 1989].

Therefore, there has been a strong demand for the development of a high-performance, chemically-amplified positive resist material which does not have such drawbacks. In response to such a demand, Ito et al. Have proposed a chemically amplified type in which an onium salt is added to a poly (butoxycarbonyloxystyrene) (called PBOCST) resin in which the OH group of polyhydroxystyrene is protected by t-butoxycarbonyl group. Proposal of positive resist materials (Polymers in Electronics, AC
S symposium series [Polymers in
Electriconics, ACS sympososiu
m Series) 242 (American Chemical Society, Washington DC. 1984), p. 11].

However, since the above-mentioned onium salt contains antimony as a metal component, it has a drawback of contaminating the substrate. In addition, Ueno et al.
Styreneoxytetrahydropyranyl) as the main component,
A positive type resist material for deep ultraviolet rays obtained by adding an acid generator to this has been proposed (36th Joint Lecture Meeting of Japan Society of Applied Physics, 1989, 1p-k-7).

However, the above positive type resist material has a drawback that it is easy to invert from a positive type to a negative type with respect to deep ultraviolet rays, electron beams or X-rays. As mentioned above,
In addition to the above-mentioned drawbacks, the two-component positive resist composition comprising a resin having an OH group protected by a protecting group and an acid generator requires decomposition of many protecting groups in order to be dissolved in a developing solution. Therefore, in the LSI manufacturing process, there is a drawback that the film thickness of the resist is changed and stress and bubbles are easily generated in the film.

Therefore, as a chemically amplified positive resist material which has improved the drawbacks of the above two-component positive resist material, a three-component positive resist material comprising an alkali-soluble resin, a dissolution inhibitor and an acid generator is used. Is being developed. As such a three-component positive resist material, a resist material (RAY / P) containing a novolac resin, an acetal compound as a dissolution inhibitor and an acid generator is added.
F resist material: Hoechst) has been developed for X-ray lithography.

However, since this resist material undergoes chemical amplification at room temperature, the resist sensitivity remarkably depends on the time from X-ray exposure to development. Therefore, it is necessary to control the time strictly at all times, but it is difficult to control the time, so that the dimension of the pattern cannot be stabilized, and the absorption of the KrF excimer laser light (wavelength 248 nm) is not possible. Due to its large size, it has a drawback that it is unsuitable for use in lithography using the laser.

By the way, in general, for chemical amplification,
Heat treatment is often required after exposure. In this case, although the number of steps is increased as compared with the case of a resist material which is chemically amplified at room temperature, it is not necessary to strictly control the time from exposure to development, so that the resist characteristics are stable. .

Further, in the case of a system in which hydrolysis is performed in the process of performing chemical amplification, water is required for hydrolysis, so it is necessary to include water in the resist material. However, as the solvent used when applying the resist material to the substrate, an organic solvent that is generally insoluble in water such as ethoxyethyl acetate is often used, and the resin itself used as the resist material is also incompatible with water. Therefore, it is difficult to contain water in the resist material, and even if it is contained, the control of the water becomes complicated.

On the other hand, in the decomposition reaction of the t-butoxycarbonyloxy group, the reaction proceeds with the two components of the t-butoxycarbonyloxy group and the acid which is the catalyst and does not require water, so that chemical amplification is performed. It is suitable for Further, since many compounds having a t-butoxycarbonyloxy group have an effect of inhibiting the solubility of the novolak resin, it is known that the t-butoxycarbonyloxy group has a dissolution inhibiting effect on the novolak resin. Has been.

From such a viewpoint, Schlegel (Sch
legel) is a novolac resin, bisphenol A
We have proposed a three-component posi type resist material consisting of a dissolution inhibitor with a t-butoxycarbonyl group introduced into it and pyrogallol methanesulfonate (Spring Lee 1990, The 37th Annual Meeting of the Japan Society for Applied Physics). , 28p-
ZE-4). However, in this case, it is difficult to put it into practical use because the light absorption of the novolac resin is large.

Further, Schwarm et al. Have developed bis (pt-butoxycarbonyloxyphenyl) iodonium hexafluoroantimonate as a material that serves as both a dissolution inhibitor and an acid generator [Polymer Fore Microelectronics
r for Microelectronics), Tokyo, 1989, Session A38], and proposes a positive resist material for deep ultraviolet rays in which this is mixed with a novolac resin. However, the above-mentioned positive resist material has a drawback that it is difficult to put into practical use because the novolak resin has a large light absorption and contains a metal.

[0017]

Therefore, as a result of intensive studies to solve the drawbacks of the conventional chemically amplified positive resist materials for high energy rays, the present inventors have found that a specific resin, a dissolution inhibitor, and an onium are used. The inventors have found that a high-energy ray positive resist material having unprecedentedly high sensitivity, high resolution, and excellent process suitability can be produced by combining a salt, and arrived at the present invention. Therefore, an object of the present invention is to provide a positive resist material for high energy rays, which has unprecedentedly high sensitivity, high resolution and excellent process suitability.

[0018]

The above objects of the present invention are as follows.
A poly (hydroxystyrene) resin a in which some of the hydrogen atoms of the hydroxyl groups are replaced with t-butoxycarbonyl groups, a dissolution inhibitor b, and an onium salt c are added in a weight fraction of 0.55 ≦.
a, 0.07 ≦ b ≦ 0.40, 0.005 ≦ c ≦ 0.1
5 and a so that a + b + c = 1, and
A positive resist material which can be developed with an aqueous alkaline solution and is sensitive to high energy rays, wherein the dissolution inhibitor b has at least one t-butoxycarbonyloxy group in one molecule, and the onium This is achieved by a positive resist material, wherein the salt c is an onium salt represented by the general formula (R) n AM. R in the above general formula is an aromatic group or a substituted aromatic group,
Each R may be the same or different. A is sulfonium or iodonium, and M is a tosylate group.

Specific examples of the above-mentioned onium salt c include diphenyl (p-methoxyphenyl) sulfonium tosylate, phenyl (p-fluorophenyl) iodonium tosylate, phenyl (p-methoxyphenyl) iodonium tosylate and diphenyl (p. --Fluorophenyl) sulfonium tosylate, diphenyl (p-hydroxyphenyl) sulfonium tosylate, phenyl (p
—Thiophenoxyphenyl) sulfonium tosylate and the like.

The content of onium salt in the resist material is
It is preferably in the range of 0.5 to 15% by weight. If the content is less than 0.5% by weight, the sensitivity of the resist material cannot be improved, and if it is 15% by weight or more, the cost of the resist material increases and the mechanical strength of the resist film decreases.

Onium salts other than the onium salt represented by (R) nAM include (C ₆ H ₅ ) ₂ I ⁺ -O ₃ SC
_{F 3, (C 6 H 5} ) 2 S + - O 3 SCF 3, (C 6 H 5 S
_{C 6 H 4) (C 6} H 5) 2 S + - O 3 SCF 3, (C 6 H
₅ ) ₂ I ⁺ -PF ₆ , (t- (CH ₃ ) ₃ -C ₆ H ₅ ) ₂
There are onium salts each represented by I ⁺ -O ₃ SCF ₃ ,
When any of these is used, it is impossible to obtain a good positive-type chemically amplified resist material for high energy rays.

The dissolution inhibitor is preferably a compound having one or more t-butoxycarbonyloxy groups in one molecule. Specifically, a hydrogen atom in the hydroxyl group of bisphenol A is replaced with a t-butoxycarbonyl group. , T-butoxycarbonyl group introduced to phloroglucin, and t- to tetrahydroxybenzophenone
Examples thereof include those having a butoxycarbonyl group introduced.
The content of the dissolution inhibitor b in the resist material is preferably in the range of 7-40% by weight. If the content is less than 7% by weight, the dissolution inhibiting effect is small, and if it is 40% by weight or more, the mechanical strength and heat resistance of the resist film are lowered.

Polyhydroxystyrene resin a in which hydrogen atoms of some hydroxyl groups are substituted with t-butoxycarbonyl groups
The substitution ratio of t-butoxycarbonyl group is 10 to
Those in the range of 50 mol% are preferable. When the substitution rate is 50 mol% or more, the solubility in an alkaline aqueous solution is lowered, so that the sensitivity of the resist material is lowered when the development is carried out using a commonly used developing solution. On the other hand, when the substitution rate is 10 mol% or less, the dissolution inhibiting effect is small. The weight average molecular weight of the polyhydroxystyrene used is preferably 10,000 or more from the viewpoint of obtaining a heat resistant resist film, and the molecular weight distribution is monodisperse from the viewpoint of forming a highly accurate pattern. Is preferred.

When polyhydroxystyrene having a wide molecular weight distribution, such as that obtained by radical polymerization, is used, the resist material contains a large molecular weight which is difficult to dissolve in an alkaline aqueous solution. It will cause hem pulling after formation. Therefore, it is preferable to use monodisperse polyhydroxystyrene as obtained by living polymerization.

Incidentally, in the present invention, a resist material using polyhydroxystyrene obtained by living polymerization (for example, one having an average molecular weight of 10,000 and a molecular weight distribution of 1.1) is used, and a resist material of 0.2 μm is used. When the pattern of the line and the space is formed, it is possible to form the pattern with good precision without the hem. Moreover, even if the pattern thus obtained is baked at 150 ° C. for 10 minutes, no deformation is observed in the pattern and the heat resistance is sufficient.

On the other hand, a resist material using polyhydroxystyrene obtained by radical polymerization (for example, one having an average molecular weight of 12,000 and a molecular weight distribution of 3.0) was used to obtain a line of 0.5 μm. When the space pattern is formed, the heat resistance of the pattern is almost the same, but since the hem is visible, a resolution of 0.2 μm cannot be obtained.

The monodispersity means that the molecular weight distribution is Mw / Mn.
= 1.05 to 1.50. However, M
w is the weight average molecular weight of the polymer, and Mn is the number average molecular weight. In the case of living polymerization, the weight average molecular weight can be easily calculated by calculating from the weight of the monomer and the number of moles of the initiator, or by using the light scattering method. Moreover, the number average molecular weight is easily measured using a membrane osmometer.

The molecular weight distribution can be evaluated by gel permeation chromatography (GPC), and the molecular structure is determined by infrared absorption (IR) spectrum or ¹ H.
-It can be easily confirmed by the NMR spectrum. As a method for obtaining a monodisperse polymer, firstly, a method of fractionating a polymer having a wide molecular weight distribution obtained by polymerization by a radical polymerization method or the like, and secondly, a polymer which is originally monodisperse by a living polymerization method. The living polymerization method is preferably used because the step of monodispersion is simple.

Even if the p-hydroxystyrene monomer is subjected to living polymerization as it is, the hydroxyl group of the monomer reacts with the polymerization initiator, so that the polymerization is not started.
Therefore, a method is used in which a monomer introduced with a protective group for protecting the hydroxyl group is subjected to living polymerization and then the protective group is eliminated to obtain the target parahydroxystyrene.

Examples of the protective group used include a tertiary butyl group, a dimethylphenylcarbylmethylsilyl group, a tertiary butoxycarbonyl group, a tetrahydropyranyl group and a tertiary butyldimethylsilyl group. For example, it can be easily obtained by subjecting a monomer represented by the following Chemical Formula 1 or Chemical Formula 2 to living anionic polymerization and then eliminating a dimethylphenylcarbylsilyl group or a t-butyl group.

[0031]

[Chemical 1]

[Chemical 2]

In the above living anionic polymerization, it is preferable to use an organometallic compound as a polymerization initiator. Preferred organometallic compounds include, for example, n-butyllithium, sec-butyllithium, tert-butyllithium, sodium naphthalene, anthracene sodium, α-methylstyrenetetramage sodium,
Examples thereof include organic alkali metal compounds such as cumyl potassium and cumyl cesium.

Living anionic polymerization is preferably carried out in an organic solvent. The organic solvent used in this case is a solvent such as aromatic hydrocarbon, cyclic ether, and aliphatic hydrocarbon, and specific examples thereof include, for example, benzene, toluene, tetrahydrofuran, dioxane, tetrahydropyran, dimethoxyethane, n-. Hexane, cyclohexane and the like can be mentioned.

These organic solvents may be used alone or in combination, but it is particularly preferable to use tetrahydrofuran. Monomer concentration during polymerization is 1
Appropriately ˜50 wt%, especially 1˜30 wt%, and the reaction is preferably carried out under high vacuum or in an atmosphere of an inert gas such as argon or nitrogen with stirring.

The reaction temperature can be arbitrarily selected within the range of -100 ° C to the boiling temperature of the organic solvent used. Especially when a tetrahydrofuran solvent is used
It is preferable to carry out the reaction at 78 ° C to 0 ° C and at room temperature when a benzene solvent is used. By carrying out the reaction for about 10 minutes to 7 hours under the above conditions, only the vinyl group selectively reacts and polymerizes to obtain a polymer represented by the following chemical formula 3 or chemical formula 4.

[0036]

[Chemical 3]

[Chemical 4]

When the desired degree of polymerization is reached, a living polymer having a desired molecular weight is obtained by stopping the polymerization reaction by adding a polymerization reaction terminator such as methanol, water or methyl bromide to the reaction system. be able to. Further, the living polymer can be purified and isolated by precipitating the obtained reaction mixture with an appropriate solvent (for example, methanol), washing and drying.

In the polymerization reaction, the monomer content is 100%.
The reaction yields a living polymer of about 10
It is 0%. Therefore, the molecular weight of the living polymer obtained can be appropriately adjusted by adjusting the amount of the monomer used and the number of moles of the reaction initiator. The molecular weight distribution of the living polymer thus obtained is monodisperse (Mw / Mn = 1.05 to 1.50).

Further, by cleaving the ether bond of the dimethylphenylcarbinylvinyldimethylsilyl group or the t-butyl group of the polymer represented by the chemical formula 3 or 4, the poly (p-hydroxy group represented by the following chemical formula 5 is obtained. Styrene) can be obtained.

[Chemical 5]

The above reaction for cleaving the ether bond is carried out by dissolving the polymer represented by Chemical formula 3 or Chemical formula 4 in a solvent such as dioxane, acetone, acetonitrile, benzene or a mixed solvent thereof, and then adding hydrochloric acid or hydrobromic acid. Alternatively, it can be easily carried out by adding an acid such as paratoluenesulfonic acid pyridinium salt dropwise. In the above reaction,
The resulting poly (p-hydroxystyrene) is monodisperse because the polymer backbone is not cleaved and no intermolecular crosslinking reactions occur.

Substitution of a hydrogen atom in a hydroxyl group of poly (hydroxystyrene) with a t-butoxycarbonyl group is a method of protecting a functional group generally used in peptide synthesis, that is, poly (hydroxystyrene) in a pyridine solution. Is easily achieved by reacting with di-t-butyl dicarbonate. Pattern formation on a substrate using the resist material of the present invention can be easily performed by the following method. That is, a resist material solution is spin-coated on a substrate and then pre-baked to obtain a coated substrate.

When the obtained coated substrate is irradiated with a high energy ray, the acid generator in the coated film decomposes to produce an acid.
Next, when the substrate is exposed to heat and then subjected to heat treatment, the t-butoxycarbonyloxy group is decomposed by using the generated acid as a catalyst and the dissolution inhibiting effect of the resist disappears, whereby a substrate on which a latent image is formed is obtained. Then, the substrate having the latent image is developed with an alkaline aqueous solution and washed with water to form a positive pattern. Next, a method for synthesizing the monodisperse poly (hydroxystyrene) that can be used in the present invention will be described.

Synthesis Example 1 Into a monodisperse poly (p-hydroxystyrene) synthesis reactor, charge dimethylformamide as a solvent together with imidazole, add p-hydroxystyrene and dimethylphenylcarbyldimethylchlorosilane in an equimolar amount thereto, and react at room temperature for 6 hours. Let

The reaction product obtained was distilled under reduced pressure to give 0.1
p-Vinylphenoxydimethylphenylcarbyldimethylsilane (monomer) having a boiling point of 130 ° C. under a pressure of mmHg was obtained in a yield of 70%. The monomer obtained as described above was further distilled in the presence of CaH ₂ and then purified using sodium benzophenone to obtain a monomer from which impurities such as water were removed.

Poly (p-vinylphenoxydimethylphen )
Synthesis of Nylcarbyldimethylsilane) In a 1-liter flask, 550 ml of tetrahydrofuran as a solvent and 8.5 × 10 ⁻⁴ mol of n-butyllithium as a polymerization initiator were charged, and the mixture was cooled to −78 ° C. When 30 g of the p-vinylphenoxydimethylphenylcarbyldimethylsilane monomer (dissolved in 50 ml of tetrahydrofuran and cooled to −78 ° C.) was added and the living polymerization reaction was carried out for 1 hour, the solution turned red. .

After confirming that the desired degree of polymerization has been reached,
Methanol was added to the reaction solution to terminate the living polymerization reaction. Next, the obtained reaction mixture was poured into methanol to precipitate the polymer, which was separated and dried to obtain 24.5 g of a white polymer. ¹ H-NMR of the obtained polymer was measured, and the results are shown in Table 1. In the polymer, only the vinyl group in the styrene portion was reacted, and the active end was reacted with the dimethylphenylcarbyldimethylsilyl group. It was confirmed to be poly (p-vinylphenoxydimethylphenylcarbyldimethylsilane) which remained without any treatment.

[0047]

[Table 1] The number average molecular weight measured by the membrane osmometry is 1
It was 1,000 g / mol.

Synthesis of poly (p-hydroxystyrene) 20 g of synthesized poly (p-vinylphenoxydimethylphenylcarbyldimethylsilane ) was added to 250 ml of acetone.
, A small amount of hydrochloric acid was added at 60 ° C., and the mixture was stirred for 6 hours. Then, the solution was poured into water to precipitate a polymer, which was washed, separated and dried to obtain 8 g of a polymer. The molecular weight distribution (Mw / of the polymer obtained from the GPC elution curve (FIG. 1))
Mn) was 1.10, and it was confirmed that the monodispersity of the polymer was extremely high.

Further, in the ¹ H-NMR spectrum of the obtained polymer, the peak derived from the dimethylphenylcarbyldimethylsilyl group disappeared. From these results, it was confirmed that the obtained polymer was monodisperse poly (p-hydroxystyrene). The number average molecular weight of the obtained polymer by the membrane osmometry is 1.
It was 4 × 10 ⁴ g / mol.

Synthesis Example 2 Synthesis of monodisperse poly (p-hydroxystyrene) Synthesis of poly (pt-butoxystyrene) In a 2 liter flask, 1,500 ml of tetrahydrofuran as a solvent and n-butyllithium 4 × 10 ⁻ as a polymerization initiator. ^After charging ³ mol, cooling to −78 ° C., distilling in the presence of CaH ₂ and then purifying with sodium benzophenone to remove impurities such as water.
80 g of t-butoxystyrene monomer (dissolved in 50 ml of tetrahydrofuran and cooled to −78 ° C.) was added, and the living polymerization reaction was carried out for 2 hours. 80 g was obtained.

When the ¹ H-NMR of the obtained polymer was measured, it was found that only the vinyl group in the styrene portion of the obtained polymer reacted, and the t-butyl group bonded to the ether had an active terminal. It was confirmed to be poly (pt-butoxystyrene), which was left without any treatment.

Synthesis of poly (p-hydroxystyrene ) 12 g of poly (pt-butoxystyrene) synthesized as described above was dissolved in 250 ml of acetone, and a small amount of hydrochloric acid was added at 60 ° C. and stirred for 8 hours. The solution was poured into water to precipitate a polymer, which was washed, separated and dried to obtain 8 g of a polymer. The molecular weight distribution (Mw / Mn) of the polymer obtained from the GPC elution curve (FIG. 2) was 1.08, and it was confirmed that the monodispersity of the polymer was extremely high.

In the ¹ H-NMR spectrum of the obtained polymer, the peak derived from t-butyl group disappeared. From these results, it was confirmed that the obtained polymer was poly (p-hydroxystyrene) having extremely high monodispersity. The number average molecular weight of the obtained polymer measured by the membrane osmometry was 5 × 10 ⁴ g / mol.

Synthesis Example 3 T-butoxyl to poly (p-hydroxystyrene)
Into a reaction vessel for introducing a bonyl group, 40 ml of pyridine was charged, 5 g of poly (p-hydroxystyrene) synthesized in Synthesis Example 1 was added and dissolved, and di-t-butyl dicarbonate 1 was added at 45 ° C. with stirring.
g (about 22 mol%) was added, and the mixture was reacted in a nitrogen stream for 1 hour. A gas was generated at the same time when di-t-butyl dicarbonate was added.

The resulting reaction solution was dropped into 1 liter of an aqueous solution containing 20 g of concentrated hydrochloric acid to precipitate a polymer,
Filtration gave a white product. The obtained product was dissolved in 50 ml of acetone and then added dropwise to 1 liter of water,
After the polymer was precipitated, it was filtered and dried under vacuum at 40 ° C. or below to obtain poly (p
-Hydroxystyrene) was obtained. From the area ratio of the aliphatic protons to the aromatic protons in the ¹ H-NMR spectrum of the obtained poly (p-hydroxystyrene), it was confirmed that the introduction rate of t-butoxycarbonyl group was 19.6%.

[0056]

INDUSTRIAL APPLICABILITY The positive resist composition of the present invention has high sensitivity to high energy rays, particularly to deep ultraviolet rays having a short wavelength (KrF excimer laser, etc.), and
It is a resist material suitable for fine processing of substrates used for LSI and the like because it absorbs little deep ultraviolet rays. Further, the positive resist composition of the present invention does not contain a metal element, has little time dependence after exposure, and does not require water in the chemical amplification process. It is a positive resist material that is extremely suitable for processing processes.

[0057]

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.
In Examples 1 to 23, the poly (p-hydroxystyrene) having a t-butoxycarbonyl group introduction rate of 19.6% obtained in Synthesis Example 3 as the base resin, and Examples 24 to 33. In the poly (p-hydroxystyrene) having a t-butoxycarbonyl group introduction rate of 40%, and in Examples 34 to 35, the poly (p-hydroxystyrene) obtained in Synthesis Example 2 was 20 mol% and 40 mol%. The introduction rate of t
-Butoxycarbonyl group-introduced products were used.

Example 1. 81 parts by weight of base resin, 14 parts by weight of 2,2-bis [p- (t-butoxycarbonyloxy) phenyl] propane, 5 parts by weight of diphenyl (p-methoxyphenyl) sulfonium tosylate, and 400 parts by weight of ethoxyethyl acetate are added. Add the mixed resist solution to the silicone substrate
Spin coating at 00 rpm and 85 on hot plate
Pre-bake at ℃ for 1 minute, the resist film thickness is 0.7
A resist-coated substrate of μm was obtained.

After drawing on the coated side of the obtained coated substrate using a KrF excimer laser, heat treatment was performed at 85 ° C. for 2 minutes. Then, development was carried out for 1 minute using an aqueous solution of tetramethylammonium hydroxide (TMAH) 2.4% by weight, followed by washing with water for 30 seconds to obtain a silicone substrate (pattern substrate) on which patterns were formed. The pattern of the obtained substrate shows positive characteristics, and the D ₀ sensitivity of the resist film is 15
It was mJ / cm ² . When a 30 kv electron beam was used instead of the KrF excimer laser, the electron beam sensitivity of the resist film was 6 μC / cm ² . Further, the electron beam sensitivity when the heat treatment after drawing is 85 ° C. for 5 minutes is 4.
It was 5 μC / cm ² .

When the KrF excimer laser was used, the obtained patterns had a line and space patterns and hole patterns each having a resolution of 0.25 μm, and had vertical sidewalls. The resolution when using an electron beam was 0.2 μm. The dissolution rate of the base resin used in the developer before prebaking was 35 nm / sec. The dissolution rate of the resin after prebaking was 1.5 nm / sec in the unexposed area and 23 nm / sec in the exposed area after heat treatment. It was seconds.

Examples 2-4. 2,2 used in Example 1
A resist solution was prepared in exactly the same manner as in Example 1 except that the dissolution inhibitors shown in Table 2 below were used instead of bis [p-butoxycarbonyloxy) phenyl] propane.
A pattern substrate was prepared and evaluated.

[0062]

[Table 2]

In the case of Example 2, the KrF excimer laser sensitivity is 200 mJ / cm ² , and the electron beam sensitivity is 6.6 μm.
It was C / cm ² . Dissolution rate when unexposed is approximately 1 nm /
It was found that the dissolution rate of the base resin was reduced to 1/35 by adding the dissolution inhibitor used here. It was also confirmed that a pattern having vertical sidewalls can be formed in the case of exposure with KrF, and that the performance with respect to resolution and the like is the same as in the case of Example 1.

In the cases of Examples 3 and 4, the KrF excimer laser sensitivity was 50 mJ / cm ² and 60 mJ / cm ^2, respectively.
cm ² and electron beam sensitivity are 25 μC / cm ² and 31 respectively.
It was μC / cm ² . As described above, in the case of Examples 3 and 4, the solubility of the polymer dissolution inhibitor was significantly lower than that of the low molecular weight dissolution inhibitor because the solubility in the 2.4% TMAH aqueous solution was extremely low. Turned out to be much larger.

Examples 5-9. A resist solution was prepared in the same manner as in Example 1 except that the onium salts shown in Table 3 were used instead of the diphenyl (p-methoxyphenyl) sulfonium tosylate used in Example 1 to prepare a pattern substrate. And evaluated. As a result, the resist sensitivity is higher when the trifluoromethanesulfonate-based onium salt is used than when the tosylate-based one is used, while the tosylate-based one has an overhang even when the heat treatment temperature after exposure is increased. It turned out that it was difficult to form it. The performance with respect to resolution and the like was about the same as in Example 1. The results are as shown in Table 3.

[0066]

[Table 3]

Examples 10 to 15. A resist solution was prepared in the same manner as in Example 1 except that the ratios of the components used in Example 1 were changed to those shown in Table 4, and a pattern substrate was prepared, and then a KrF excimer laser was used. evaluated. The results are as shown in Table 4. The heat treatment after exposure is 8
It was performed at 5 ° C. for 2 minutes. The resolution when developed with a 2.4% TMAH aqueous solution for 1 minute was almost the same as that in Example 1.

[0068]

[Table 4]

Examples 16 to 25. Instead of the base resin used in Example 1, the introduction rate of t-butoxycarbonyl group was 4
A resist solution was prepared in the same manner as in Example 1 except that 0 mol% of poly (p-hydroxystyrene) was used and the component ratios were changed as shown in Table 5, and a pattern substrate was prepared to prepare a KrF excimer laser. The sensitivity when using was evaluated. The results are as shown in Table 5.

[0070]

[Table 5]

In the case of the present embodiment, Embodiments 10 to 1 are used.
The sensitivity is lower than that of No. 5. It is speculated that this is because the solubility of the base resin is large and the solubility in the alkaline aqueous solution is lowered. However, the resolution was about the same as that of Example 1, and the pattern shape was closer to the rectangular shape than that of Examples 10 to 15. When using an electron beam, 0.2
It was able to resolve a pattern of μm or less. The dissolution rate of the base resin used in the developing solution was 15 nm / sec.

Examples 26 and 27. Other than using the resin obtained by introducing 20 mol% of t-butoxycarbonyl group (Example 26) and the resin obtained by introducing 40 mol% (Example 27) into the poly (p-hydroxystyrene) obtained in Synthesis Example 2, respectively. A resist solution was prepared in the same manner as in Example 1, and a pattern substrate was prepared and evaluated.

In Examples 26 and 27, the KrF excimer laser sensitivity was 20 mJ / cm ² and 25 mJ, respectively.
/ Cm ² and electron beam sensitivity were both 8 μC / cm ² .
From this result, it was found that the case of using the poly (p-hydroxystyrene) obtained in Synthesis Example 2 had lower sensitivity. When the KrF excimer laser was used, the obtained pattern was capable of resolving 0.3 μm line and space patterns and hole patterns, and also had vertical side walls. In the case of using the electron beam, the pattern of 0.2 μm lines and spaces could be resolved.

[Brief description of drawings]

FIG. 1 is a GPC elution curve of the polymer synthesized in Synthesis Example 1.

FIG. 2 is a GPC elution curve of the polymer synthesized in Synthesis Example 2.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location G03F 7/029 H01L 21/027 (72) Inventor Jun Watanabe 3-2 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa No. 1 Shin-Etsu Chemical Co., Ltd. Corporate Research Center (72) Inventor Minoru Takamizawa 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Shin-Etsu Chemical Co., Ltd. Corporate Research Center (72) Inventor Kei Tanaka Tokyo Nihon Telegraph and Telephone Corporation, 1-1-6 Uchisaiwaicho, Chiyoda-ku (72) Inventor Yoshio Kawai 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor, Masato Matsuda Tokyo 1-1-6 Uchisaiwaicho, Chiyoda-ku, Nihon Telegraph and Telephone Corporation

Claims (2)

[Claims] 1. A poly (hydroxystyrene) resin a in which some of the hydrogen atoms of the hydroxyl groups are substituted with t-butoxycarbonyl groups, a dissolution inhibitor b and an onium salt c, each in a weight fraction of 0.55 ≦ a. , 0.07 ≦ b ≦ 0.40, 0.005
≦ c ≦ 0.15 and a + b + c = 1 so that it can be developed and developed with an alkaline aqueous solution.
A positive resist material sensitive to high energy rays, wherein the dissolution inhibitor b has at least one t-butoxycarbonyloxy group in one molecule, and the onium salt c is represented by the general formula (R) n AM A positive resist material characterized by being an onium salt represented by the formula; wherein R is an aromatic group or a substituted aromatic group, and each R may be the same or different. A is sulfonium or iodonium, and M is a tosylate group. 2. The positive resist material according to claim 1, wherein the poly (hydroxystyrene) is a monodisperse poly (hydroxystyrene) obtained by a living polymerization reaction.