JPH06236033A - Positive resist material - Google Patents

Abstract

PURPOSE:To provide a positive resist material for high energy beam high in sensitivity and resolution and having excellent process aptitude. CONSTITUTION:The positive resist material contains a poly(hydroxy styrene) resin (a) in which hydrogen atom of a part of hydroxyl group is substituted by t-butoxycarbonyl, a dissolution inhibitor (b) and an onium salt (c) so as to be 0.55<=(a), 0.07<=(b)<=0.40, 0.005<=(c)<=0.15 and (a)+(b)+(c)=1 by wt. percent, is developed with an alkaline aq. solution and is sensitive to high energy beam and the onium salt (c) is expressed by a general formula, (R)2IM. In the formula, R is aromatic group, at least one of R's is phenyl group substituted by t-butoxy group and each of Rs can be the same or different. And M is an anion.

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, the pattern rule with a resolution of about 0.5 μm 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 wavelength shorter than that of g-line or i-line, is regarded as promising. According to deep-UV lithography, it is possible to form a pattern rule of 0.1 to 0.3 μm, and when a resist material having low light absorption is used, it has a side wall that is almost vertical to the substrate. It is possible to form patterns. Further, since the patterns can be transferred at one time, the pattern formation processing efficiency (throughput) is superior to the lithography using the electron beam. In addition, in recent years, since it has become possible to use a high-intensity KrF excimer laser as a light source for far-ultraviolet rays, light absorption is particularly small from the viewpoint of mass-producing LSIs using the light source.
It is said that it is necessary to use a resist material having high sensitivity.

Therefore, in recent years, a chemically amplified resist material has been developed which has sensitivity equal to or higher than that of a conventional high-sensitivity resist material, and has high resolution and high dry etching resistance and which is produced using an acid as a catalyst (for example, , Liu (L
iu), etc., Journal of Vacuum Science and Technology (J. Vac. Sci. Tec)
hno. ), Vol. B6, p. 379, 1988), a chemically amplified negative resist material (SAL601ER7: manufactured by Shipley Co., Ltd.) consisting of three components of a novolak resin, a melamine compound and an acid generator by Shipley Co. The product name) has already been commercialized.

However, when a negative resist material is used in the LSI manufacturing process, it is easy to form wiring 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 dimensional controllability during substrate processing using dry etching. Not only the damage to the computer, but also the tendency to cause the pattern to collapse [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 disclosed a chemically amplified type obtained by adding an onium salt to a poly (butoxycarbonyloxystyrene) (PBOCST) resin obtained by protecting the OH group of polyhydroxystyrene with a t-butoxycarbonyl group. Proposal of positive resist materials (Polymers in Electronics, ACS Symposium Series [Polymers in El
electricalonics, ACS symposium
Series) 242 (American Chemical Society, Washington DC. 1984), p. 11].

However, since the above-mentioned onium salt contains antimony as a metal component, it not only contaminates the substrate, but also the above-mentioned resist material has the drawback that the change with time after irradiation with far-ultraviolet rays is extremely large. there were.
Also, Ueno et al. Have proposed a positive resist material for deep ultraviolet rays, which is mainly composed of poly (p-styreneoxytetrahydropyranyl) and to which an acid generator is added (36th Japan Society of Applied Physics). Related Joint Lecture, 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 in which an OH group is protected by a protective group and an acid generator requires the decomposition of many protective groups in order to be dissolved in a developing solution. Therefore, there are drawbacks that the film thickness of the resist is changed in the manufacturing process of the LSI, 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 containing a novolac resin, an acetal compound as a dissolution inhibitor, and an acid generator (RAY /
PF 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 order to carry out chemical amplification, heat treatment is generally required after exposure in many cases. 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 incorporate water into the resist material.

However, as the solvent used for coating the resist material on the substrate, an organic solvent which is not soluble in water, such as ethoxyethyl acetate, is generally used.
In addition, since many resins themselves used as resist materials are not compatible with water, it is difficult to add water to the resist material, and even if it is added, 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 water is not required. Is preferred.

Further, since many compounds having a t-butoxycarbonyloxy group have an effect of inhibiting the solubility of the novolak resin, the t-butoxycarbonyloxy group has a dissolution inhibiting effect on the novolak resin. It has been known. From this point of view, Schlegel et al. Proposed a three-component positive resist material consisting of a novolak resin, a dissolution inhibitor obtained by introducing a t-butoxycarbonyl group into bisphenol A, and pyrogallol methanesulfonate. (Spring Lee 1990, 37th Joint Lecture Meeting of Japan Society of 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. In addition, Schwarm and the like use bis (pt-t-) as a material that serves as both a dissolution inhibitor and an acid generator.
Butoxycarbonyloxyphenyl) iodonium hexafluoroantimonate was developed [polymer for microelectronics (polymer for
Microelectronics), Tokyo, 198.
9th session, Session A38], and proposes a positive resist material for deep ultraviolet rays in which this is mixed with a novolac resin.

However, the above positive type 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. By the way, in a three-component chemically amplified positive resist composition comprising a resin, a dissolution inhibitor and an acid generator, the acid generator used is known to have a particularly large effect on the performance as a resist material. . A typical example of such an acid generator is (C ₆ H ₅ ) ₃ S ⁺ -O ₃ S.
_{CF 3, (C 6 H 5} ) 3 S + - PF 6, (C 6 H 5) 3 S
^{_{+ - SbF 6, (C 6}} H 5 SC 6 H 4) (C 6 H 5) 2
S ⁺ -O ₃ SCF ₃ , CH ₃ OC ₆ H ₅ (C ₆ H ₅ ) ₂ S
^The compounds represented by ⁺ -OSO ₂ CF ₃ can be mentioned.

However, since any of these acid generators has any of the following drawbacks, the performance as a resist material is deteriorated. The above-mentioned drawback is caused by ethyl cellosolve acetate, ethyl lactate, methoxy-
2-Solubility in a solvent such as propanol is low, so it is difficult to add an appropriate amount to the resist, and even if the solubility in a solvent is relatively high,
It is difficult to form a good resist film because of poor compatibility with the resin for forming a resist film, and it is possible to reduce sensitivity with time after light irradiation and before heat treatment after exposure. The pattern shape is likely to change.

[0017]

Therefore, as a result of diligent research on such an acid generator, the present inventors have found that in a chemically amplified positive resist composition in which a resin, a dissolution inhibitor and an acid generator are combined, poly (hydroxy) is used. When a styrene resin and a specific onium salt are used as an acid generator, the drawbacks of the conventional chemically amplified positive resist material for high energy rays are solved, and high sensitivity and high resolution not seen in the past. And that it can be a positive resist material for high energy rays having excellent properties and excellent process suitability,
The present invention has been reached. 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 substituted with t-butoxycarbonyl, a dissolution inhibitor (b) and an onium salt (c) each weigh 1 wt.
0.50 ≦ a, 0.07 ≦ b ≦ 0.40 in the percentage
A positive resist material containing 0.005 ≦ c ≦ 0.15 and a + b + c = 1 so that it can be developed with an aqueous alkaline solution and is sensitive to high energy rays, wherein the onium salt (c ) Is the general formula (R) ₂ I
This is achieved by a positive resist material characterized by being an onium salt represented by M. In the above formula, R is an aromatic group, at least one of each R is a phenyl group substituted with a t-butoxy group, and each R may be the same or different; Is an anion.

A poly (hydroxystyrene) resin in which some hydrogen atoms of hydroxyl groups are t-butoxycarbonylated has a t-butoxycarbonylation rate of 10 to 50 mol%.
The range of is preferable. When the t-butoxycarbonylation rate is 50 mol% or more, the solubility in an alkaline aqueous solution decreases, so that the sensitivity of the resist material decreases when developing with a commonly used developing solution. On the other hand, t
-If the butoxycarbonylation rate is 10 mol% or less, the dissolution inhibiting effect is small.

The t-butoxycarbonylation of hydrogen atoms in the hydroxyl groups of poly (hydroxystyrene)
It can be easily carried out by a method of protecting a functional group as is commonly used in peptide synthesis, that is, by reacting poly (hydroxystyrene) with di-t-butyl dicarbonate in a pyridine solution. The weight average molecular weight of the poly (hydroxystyrene) resin 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. Preferably there is.

When a poly (hydroxystyrene) resin having a wide molecular weight distribution, such as obtained by radical polymerization, is used, the resist material contains a large molecular weight which is difficult to dissolve in an alkaline aqueous solution. , This causes the trailing edge after pattern formation. Therefore, it is preferable to use a monodisperse poly (hydroxystyrene) resin as obtained by living polymerization.

Incidentally, in the present invention, poly (hydroxystyrene) obtained by living polymerization (for example,
When a resist material using an average molecular weight of 10,000 and a molecular weight distribution of 1.1) is used to form a line and space pattern of 0.2 μm, there is no trailing and good accuracy is obtained. A pattern can be formed. 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 poly (hydroxystyrene) obtained by radical polymerization (for example, an average molecular weight of 12,000 and a molecular weight distribution of 3.0) is used,
When a pattern of 0.5 μm lines and spaces is formed, although the heat resistance of the pattern is approximately the same, the tailing is visible, so a resolution of 0.2 μm cannot be obtained. The monodispersity means that the molecular weight distribution Mw / Mn is 1.0.
It means 5 to 1.50. However, Mw is a weight average molecular weight of a polymer, and Mn is a number average molecular weight. The weight average molecular weight is calculated by calculating the weight of the monomer and the number of moles of the initiator in the case of living polymerization.
Alternatively, it can be easily obtained by using a 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), the molecular structure of which is infrared absorption (IR) spectrum or ¹ H
-It can be easily confirmed by the NMR spectrum. As a method of obtaining a monodisperse resin (referred to as a polymer), firstly, a method of fractionating a polymer having a wide molecular weight distribution obtained by a radical polymerization method, and a second method
Examples of the method include a method of obtaining a monodisperse polymer from the beginning by the living polymerization method. However, the living polymerization method is preferably used because the step of monodispersion is simple.

Next, a method for producing a monodisperse poly (hydroxystyrene) resin by a living polymerization method is applied to poly (p-
(Hydroxystyrene) will be described in more detail as an example.
Even if the p-hydroxystyrene monomer is subjected to living polymerization as it is to obtain poly (p-hydroxystyrene), 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. In the above living polymerization, it is preferable to use an organometallic compound as a polymerization initiator. Examples of preferable organic metal compounds include organic alkali metal compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, sodium naphthalene, anthracene sodium, α-methylstyrenetetramage sodium, cumylpotassium and cumylcesium. .

Living anionic polymerization is preferably carried out in an organic solvent. The organic solvent used in this case is a solvent such as an aromatic hydrocarbon, a cyclic ether, or an aliphatic hydrocarbon, and specific examples thereof include benzene and
Examples thereof include toluene, tetrahydrofuran, dioxane, tetrahydropyran, dimethoxyethane, n-hexane and cyclohexane. These organic solvents may be used alone or in combination, but tetrahydrofuran is particularly preferably used.

The concentration of the monomer in the polymerization is suitably 1 to 50% by weight, particularly 1 to 30% by weight, and the reaction should be carried out under high vacuum or in an atmosphere of an inert gas such as argon or nitrogen with stirring. Is preferred. The reaction temperature can be arbitrarily selected in the range of -100 ° C to the boiling temperature of the organic solvent used. In particular, the reaction is preferably carried out at -78 ° C to 0 ° C when a tetrahydrofuran solvent is used, and at room temperature when a benzene solvent is used.

By carrying out the reaction for about 10 minutes to 7 hours under the conditions as described above, only the vinyl group selectively reacts and polymerizes to obtain a polymer. When the desired degree of polymerization is reached, for example, a living polymer having a desired molecular weight can be obtained by adding a polymerization reaction terminator such as methanol, water or methyl bromide to the reaction system to stop the polymerization reaction. . 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, 100% of the monomer is used.
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, poly (p-hydroxystyrene) can be obtained by eliminating the dimethylphenylcarbyldimethylsilyl group or t-butyl group of the polymer. In the above elimination reaction, the polymer is dioxane,
It can be easily carried out by dissolving it in a solvent such as acetone, acetonitrile, benzene or a mixed solvent thereof, and then adding an acid such as hydrochloric acid, hydrobromic acid or pyridinium p-toluenesulfonic acid salt. In the above reaction, the main chain of the polymer is not cleaved and the crosslinking reaction between the molecules does not occur, so that the obtained poly (p-hydroxystyrene) is monodisperse.

As the dissolution inhibitor (b) used in the present invention, an alkali aqueous solution is used when the resist film is irradiated with high energy rays such as deep ultraviolet rays and, if necessary, heat-treated and then treated with an alkali developing solution. A substance which becomes soluble in As such a dissolution inhibitor,
Di-t-butoxycarbonylhydroquinone, 4,4'-
Di-t-butoxycarbonyloxybiphenyl, di-t
-Phenols protected by a t-butoxycarbonyl group such as butoxycarbonylbisphenol A, di-t-butoxycarbonylbisphenol F; cholic acid-
Bile acid derivatives such as t-butyl ester and deoxycholic acid-t-butyl ester, and tetrahydropyranyl group, methoxymethyl group, t- such as 4-t-butoxycarbonylbiphenyl and di-t-butoxyacetylbisphenol A. Examples thereof include esters protected with a butyl group or a t-amyl group.

The content of the dissolution inhibitor in the resist material of the present invention is preferably in the range of 7-40% by weight. Content is 7
If it is less than wt%, the dissolution inhibiting effect is small, and if it is 40 wt% or more, the mechanical strength and heat resistance of the resist film are lowered. In the general formula of the iodonium salt used in the present invention, R is an aromatic group, at least one of which is a phenyl group substituted with a t-butoxy group, and each R may be the same or different. . Further, M is an anion of iodonium.

As the aromatic group, a phenyl group, a 3-methylphenyl group, a 4-methylphenyl group, a 4-isopropylphenyl group, a 4-t-butylphenyl group, a 4-fluorophenyl group, a 3-fluorophenyl group, 4-chlorophenyl group, 2-methoxyphenyl group, 3-methoxyphenyl group, 4-methoxyphenyl group, 4-phenoxyphenyl group, 4-phenylthiophenyl group, 3-trifluoromethylphenyl group, 4-trifluoromethylphenyl group Groups and the like.

The anion of iodonium is not particularly limited as long as it is an anion having no nucleophilicity, and specifically, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate. , Trifluoromethanesulfonate, paratoluenesulfonate, tetrafluoroborate, fluorosulfonate and the like. Among these, it is particularly preferable to use trifluoromethanesulfonate or paratoluenesulfonate from the viewpoint of preventing contamination of the substrate with metal ions.

The content of the onium salt in the resist material of the present invention 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. 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 iodonium salt (acid generator) in the coated film is decomposed to generate an acid. Then, when heat treatment is performed, a substrate having a latent image formed by the decomposition of the t-butoxycarbonyloxy group using the generated acid as a catalyst and the dissolution inhibiting effect of the resist disappearing 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.

The reason why the resist material of the present invention using an iodonium salt is excellent in sensitivity and resolution to high energy rays is not necessarily clear, but the iodonium salt used in the present invention is a solvent used for coating the resist material. , A poly (hydroxylene) resin and a dissolution inhibitor have good compatibility, so that a uniform resist film can be formed, and an iodonium salt in a resist material produces an acid by light irradiation, Since the t-butyl group of the resin is decomposed to generate a phenolic hydroxyl group, the light-irradiated portion has an excellent dissolution inhibiting effect even though the light-irradiated portion has an excellent dissolution inhibiting effect. It is presumed that the effect disappears and the dissolution rate in the alkaline aqueous solution increases.

[0039]

The positive resist material of the present invention has a high sensitivity to high energy rays, and particularly to a deep ultraviolet ray (KrF excimer laser etc.) having a short wavelength. In addition, the plasma etching resistance and the heat resistance of the resist pattern are excellent, and the absorption of the far ultraviolet rays is small.
It is a resist material suitable for fine processing of substrates used for SI and the like. Further, since the positive resist composition of the present invention does not contain a metal element and has little time dependency after exposure and does not require water in the chemical amplification process, it is possible to reduce the amount of fine energy of a substrate used for LSI or the like due to high energy rays. It is a positive resist material that is extremely suitable for processing processes.

[0040]

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.
The base resin in the examples has a molecular weight of 10,000.
A resin was used in which the hydroxyl group of poly (p-hydroxystyrene) having a molecular weight distribution (Mw / Mn) of 1.05 was 20 mol% t-butoxycarbonylated.

Example 1. A resist solution containing the following composition was spin-coated on a silicon substrate at 2,000 rpm, and prebaked on a hot plate at 85 ° C. for 1 minute to form a resist having a resist film thickness of 0.7 μm. A coated substrate was obtained. Base resin 81 parts by weight, di-t-butoxycarbonylbisphenol A (dissolution inhibitor) 14 parts by weight, diphenyl (4-t-butoxyphenyl) iodonium triflate (acid generator) 5 parts by weight, ethoxyethyl acetate 400 parts by weight

After drawing on the coated side of the obtained coated substrate using a KrF excimer laser (wavelength 248 nm),
The heat treatment was performed at 85 ° C. for 2 minutes. Next, development was performed for 1 minute using an aqueous solution of tetramethylammonium hydroxide (TMAH) 2.4% by weight, followed by washing for 30 seconds with water,
A silicon substrate (pattern substrate) on which a pattern was formed was obtained. The pattern of the obtained substrate showed positive characteristics, and the D ₀ sensitivity of the resist film was 40 mJ / cm ² .

Further, in place of the KrF excimer laser, 3
When the electron beam of 0 kv was used, the Do sensitivity of the resist film was 15.2 μC / cm ² . The obtained pattern is in the case of using the KrF excimer laser,
The line and space patterns and the hole pattern each have a resolution of 0.25 μm and also have vertical sidewalls. The resolution of the pattern when an electron beam is used is 0.2.
was μm.

Examples 2-6. A resist solution was prepared in the same manner as in Example 1 except that the iodonium salt (acid generator) shown in Table 1 was used instead of the diphenyl (4-t-butoxyphenyl) iodonium triflate used in Example 1. Was prepared, a pattern substrate was prepared, and sensitivity and resolution were evaluated in exactly the same manner as in Example 1. The results of sensitivity are shown in Table 2.
As shown in. The resolution was the same as that of the first embodiment.

Examples 7-21. Instead of the base resin and the dissolution inhibitor used in Example 1, the base resin and the dissolution inhibitor shown in Tables 3 and 4 were used respectively, and diphenyl (4-t-butoxyphenyl) iodonium used in Example 1 was used. A resist solution was prepared in the same manner as in Example 1 except that the acid generators (shown in Table 1) used in Examples 1 to 6 were used instead of the triflate to prepare a pattern substrate. Then, the sensitivity and the resolution were evaluated in exactly the same manner as in Example 1. The results of sensitivity are as shown in Table 5. still,
Although there were some differences, the resolution of the line and space patterns was 0.3 μm in each case.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[Table 5]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Katsuya Takemura, Inventor Katsuya Takemura, Niigata Prefecture, Chubiki-gun, Kubiki Village, No. 28 Nishi-Fukushima 1 Shinsei Chemical Industry Co., Ltd. Synthetic Technology Laboratory (72) Minoru Takamizawa Takatsu Kawasaki, Kanagawa 3-2-1, Sakado, Shinjuku Corporate Research Center, Shin-Etsu Chemical Co., Ltd. (72) Inventor Keijun Tanaka 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Yoshio Kawai 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Ito Matsuda 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (2)

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