JP3416876B2 - Chemically amplified positive resist base resin and resist pattern forming solution using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel base resin for positive resist, more specifically, it has high sensitivity and high resolution, and also has heat resistance, depth of focus characteristics, and stability over time. In addition, the resist solution has good storage stability and is sensitive to radiation such as ultraviolet rays, far ultraviolet rays, excimer lasers such as KrF and ArF, X-rays, and electron beams that can form a resist pattern with excellent profile shape without substrate dependence. The present invention relates to a novel base resin for positive resist which gives a chemically amplified positive resist composition, and a resist pattern forming solution using the same.

[0002]

2. Description of the Related Art Conventionally, semiconductor devices such as ICs and LSIs have been subjected to photolithography using a photoresist composition,
Although the steps of etching, impurity diffusion and wiring formation are repeated several times, in this photolithography, a photoresist composition is applied onto a silicon wafer by spin coating or the like to form a thin film, which is used as a mask pattern. After that, radiation such as ultraviolet rays is irradiated and developed to form a resist pattern, and then etching is performed using the resist pattern as a protective film.

The photoresist compositions used in the photolithography so far have required a resolution of about submicron (1 μm or less) and half micron (0.5 μm or less). Line (436
nm), i-line (365 nm), and other positive-type photoresists containing an alkali-soluble novolak resin and a quinonediazide group-containing compound as basic components.

By the way, in recent years, the miniaturization of semiconductor devices has been increasing more and more, and today, it is a quarter micron (0.25 μm).
Mass production of VLSI using the following ultrafine patterns is about to start. However, in order to obtain such an ultra-fine pattern of quarter micron, it is difficult with a positive photoresist using a conventional alkali-soluble novolac resin and a quinonediazide group-containing compound as a basic component,
Far-ultraviolet rays of shorter wavelength (200-300 nm), Kr
As a resist for excimer lasers such as F and ArF, electron beams and X-rays, high resolution can be achieved, and the catalytic reaction and chain reaction of the acid generated by irradiation of radiation can be utilized, and the quantum yield Chemically amplified resists that have a sensitivity of 1 or more and that can achieve high sensitivity have attracted attention and have been actively developed, and the hydroxyl groups of poly (hydroxystyrene) have already been eliminated.
A resist composition (US Pat. No. 4,491,628) in which a resin component substituted with a t-butoxycarbonyloxy group and an acid generator such as an onium salt are combined has been proposed.

[0005]

However, the above resist composition is not sufficient in resolution and depth of focus characteristics, and when it is developed after being left for a certain period of time after exposure, it is peculiar to a chemically amplified resist. There is a defect that the pattern shape is deteriorated due to the deactivation of the acid generated by the exposure, that is, the so-called leaving stability is poor (bridging in which the upper part of the resist pattern is continuous in an eaves shape). If such bridging occurs, a desired wiring pattern cannot be obtained, which is fatal in manufacturing a semiconductor device. As a method of overcoming such a drawback, there is a method of providing a top coat layer on the resist layer in order to prevent deactivation of the acid generated by exposure, but such a method increases the number of manufacturing steps and deteriorates the throughput. In addition, the cost is high, which is not preferable. Therefore, there is a strong demand for the emergence of a resist that does not need to be provided with a top coat layer and is excellent in stability during deposition.

Further, the conventional chemically amplified resist is
There is a drawback in that a bottoming pattern is formed on a substrate provided with an insulating film such as a silicon nitride film (SiN) or boron-phosphorus-silicate glass (BPSG) or a film of titanium nitride (TiN).

Further, aluminum-silicon-copper (Al
If a substrate provided with a metal film of —Si—Cu) alloy, tungsten (W), or the like is used, there is a drawback that the pattern cross-sectional shape becomes wavy due to the influence of standing waves. As a method of improving these substrate dependence and the drawbacks of standing wave, there is a method of providing an antireflection layer between the substrate and the resist layer, but this method has the same number of manufacturing steps as the above-mentioned topcoat layer. It is not preferable because the throughput is poor and the cost is high. Therefore, there is a strong demand for a resist that does not depend on a substrate, does not need to be provided with an antireflection layer, and is resistant to the influence of standing waves and that can form a resist pattern having an excellent profile shape.

In addition, the conventional resist composition does not have sufficient resistance to heat, and when it is used as a solution,
Often, there is a drawback that the storage stability is poor such that foreign substances are generated during the storage. Therefore, there is also a strong demand for a resist composition which is excellent in heat resistance and can provide a resist solution which is free from the generation of foreign matter and is excellent in storage stability.

[0009]

[Means for Solving the Problems] In view of such a current situation,
As a result of intensive studies, the inventors of the present invention have found that the above problem is that as a base resin component for a positive resist whose solubility in an alkaline aqueous solution is increased by the action of an acid, a specific proportion of hydroxyl groups is a specific substituent. Substituted, and by using a novel poly (hydroxystyrene) having a specific weight average molecular weight and molecular weight distribution, or a specific ratio of the hydroxyl group is substituted with a substituent different from this and the substituent, and,
It can be solved by using a mixture with polyhydroxystyrene having a specific weight average molecular weight and molecular weight distribution, and it has high sensitivity, high resolution, and heat resistance, depth of focus characteristics, stability over time in leaving and resist solution. Chemical amplification that is excellent in storage stability and can form a resist pattern with excellent profile shape without substrate dependency, and sensitive to radiation such as ultraviolet rays, far ultraviolet rays, excimer lasers such as KrF and ArF, X-rays, and electron beams. The inventors have found that a positive resist composition of the positive type can be obtained, and completed the present invention.

That is, the present invention has the general formula

[Chemical 3] 10 to 60 mol% of a structural unit represented by (I) (in the formula, R ¹ is a hydrogen atom or a methyl group, R ² is a methyl group or an ethyl group, and R ³ is a lower alkyl group having 1 to 4 carbon atoms). And the expression

[Chemical 4] A poly (hydroxystyrene) derivative composed of 90 to 40 mol% of the structural unit represented by (II) and having a weight average molecular weight of 8,000 to 25,000 and a molecular weight distribution (Mw / Mn) of 1.5 or less. and it provides a resist pattern forming solution obtained by dissolving a chemically amplified positive resist base resin and a chemically amplified positive resist composition containing the same in a solvent comprising propylene glycol monomethyl ether acetate.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The base resin for a chemically amplified positive resist of the present invention comprises 10 to 60%, preferably 20 to 50% of the hydroxyl groups of poly (hydroxystyrene), represented by the general formula

[Chemical 5] (III) (in the formula, R ¹ , R ² and R ³ have the same meanings as described above)
A novel poly (hydroxystyrene) derivative obtained by substituting with a residue represented by the following formula. In the present invention, the weight average molecular weight is 8,000 to 25,000.
It is necessary to use those having a molecular weight distribution of 0 and a molecular weight distribution (Mw / Mn) of 1.5 or less. If the substitution ratio of the hydroxyl groups of this poly (hydroxystyrene) is less than 10%, a pattern having an excellent shape cannot be obtained, and if it exceeds 60%, the sensitivity of the resist is lowered, which is not preferable. It is suitable.

As the substituent of the above general formula (III),
For example, 1-methoxyethoxy group, 1-ethoxyethoxy group, 1-n-propoxyethoxy group, 1-isopropoxyethoxy group, 1-n-butoxyethoxy group, 1-isobutoxyethoxy group, 1- (1,1- Dimethylethoxy) -1-methylethoxy group, 1-methoxy-1-methylethoxy group, 1-ethoxy-1-methylethoxy group,
1-n-propoxy-1-methylethoxy group, 1-isobutoxy-1-methylethoxy group, 1-methoxy-n-
Examples thereof include a propoxy group and a 1-ethoxy-n-propoxy group. Of these, a 1-ethoxyethoxy group and a 1-methoxy-n-propoxy group are particularly preferable because the sensitivity and resolution are improved in a well-balanced manner. This base resin is
The hydroxyl group of poly (hydroxystyrene) having the weight average molecular weight and the above-mentioned molecular weight distribution is converted to the above-mentioned general formula (III) according to a known substitution reaction with, for example, 1-chloro-1-ethoxyethane or 1-chloro-1-methoxypropane. It can be produced by substituting the residue of

Of the poly (hydroxystyrene) derivative
As described above, the weight average molecular weight needs to be in the range of 8,000 to 25,000 based on polystyrene based on the gel permeation chromatography method (GPC method). If it is smaller than this, the coating property becomes insufficient, and if it is larger than this, the solubility in an alkaline aqueous solution decreases. Furthermore, to increase heat resistance,
It is necessary that the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is 1.5 or less.

The poly (hydroxystyrene) derivative (hereinafter referred to as polyhydroxystyrene A) composed of the structural unit represented by the general formula (I) and the structural unit represented by the general formula (II) has 10 to 10 hydroxyl groups. 60% is te
Poly (hydroxystyrene) substituted with rt-butoxycarbonyloxy group, ie

[Chemical 6] (IV) a structural unit of 10 to 60 mol%, and a structural unit of the general formula (II) of 90 to 40 mol%, and a weight average molecular weight of 8,000 to 25,000.
0, a poly (hydroxystyrene) derivative having a molecular weight distribution (Mw / Mn) of 1.5 or less (hereinafter referred to as polyhydroxystyrene B) may be mixed and used as a base resin for a positive resist. Use of such a base resin is advantageous because a chemically amplified positive resist composition having more excellent resolution, heat resistance and profile shape can be obtained.

This polyhydroxystyrene B is, for example,
The hydroxyl groups of poly (hydroxystyrene) having a weight average molecular weight of 8,000 to 25,000 and a molecular weight distribution (Mw / Mn) of 1.5 or less are reacted with di-tert-butyl-dicarbonate to give tert-butoxycarbonyloxy. Obtained by substituting with a group. At this time, if the substitution rate of hydroxyl groups is less than 10%, a resist pattern having an excellent profile cannot be provided, and if it exceeds 60%, the sensitivity is lowered. The preferable range of the substitution rate of the hydroxyl group is 20 to 50%. When the mixture of polyhydroxystyrene A and polyhydroxystyrene B is used, the mixing ratio is 30 to 90% by weight for the former and 7 for the latter.
0 to 10 % by weight , preferably 50 to 80% by weight ,
The latter is preferably selected within the range of 50 to 20% by weight .

The base resin of the present invention has high sensitivity and high resolution by adding a compound (hereinafter referred to as an acid generator) which generates an acid upon irradiation with radiation and an organic carboxylic acid. Chemical amplification with good storage stability as a solution
A positive resist composition can be prepared. This positive resist composition has excellent heat resistance, depth of focus width characteristics, stability upon storage over time, and gives a resist pattern having a good profile shape without substrate dependence.

Next, as the acid generator to be used with the base resin of the present invention, a chemically amplified positive type resist has been conventionally used.
It is possible to arbitrarily select and use from the known acid generators of the composition, and there is no particular limitation. Examples thereof include (a) bis (p-toluenesulfonyl) diazomethane, methylsulfonyl-p-toluenesulfonyldiazomethane, 1-cyclohexylsulfonyl-1- (1,1-dimethylethylsulfonyl) diazomethane, bis (1 , 1-Dimethylethylsulfonyl) diazomethane, bis (1-methylethylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, bis (4-ethylphenylsulfonyl) diazomethane, bis ( 3-Methylphenylsulfonyl) diazomethane, bis (4-methoxyphenylsulfonyl)
Bissulfonyldiazomethanes such as diazomethane, bis (4-fluorophenylsulfonyl) diazomethane, bis (4-chlorophenylsulfonyl) diazomethane, and bis (4-tert-butylphenylsulfonyl) diazomethane, (b) 2-methyl-2- (p -Toluenesulfonyl) propiophenone, 2- (cyclohexylcarbonyl) -2- (p-toluenesulfonyl) propane, 2-methanesulfonyl-2-methyl- (4-methylthio) propiophenone, 2,4-dimethyl-2 -(P
-Toluenesulfonyl) pentan-3-one and other sulfonylcarbonylalkanes, (c) 1-p-toluenesulfonyl-1-cyclohexylcarbonyldiazomethane, 1-diazo-1-methylsulfonyl-4-phenyl-2-butanone, 1 -Cyclohexylsulfonyl-1-
Cyclohexylcarbonyldiazomethane, 1-diazo-
1-cyclohexylsulfonyl-3,3-dimethyl-2
-Butanone, 1-diazo-1- (1,1-dimethylethylsulfonyl) -3,3-dimethyl-2-butanone, 1
-Acetyl-1- (1-methylethylsulfonyl) diazomethane, 1-diazo-1- (p-toluenesulfonyl) -3,3-dimethyl-2-butanone, 1-diazo-
1-benzenesulfonyl-3,3-dimethyl-2-butanone, 1-diazo-1- (p-toluenesulfonyl)-
3-Methyl-2-butanone, 2-diazo-2- (p-toluenesulfonyl) acetic acid cyclohexyl, 2-diazo-
2-Benzenesulfonyl acetate tert-butyl, 2-diazo-2-methanesulfonyl isopropyl acetate, 2-diazo-2-benzenesulfonyl acetate cyclohexyl, 2
-Diazo-2- (p-toluenesulfonyl) acetic acid ter
Sulfonylcarbonyldiazomethanes such as t-butyl, (d) 2-nitrobenzyl p-toluenesulfonate, 2,6-dinitrobenzyl p-toluenesulfonate, p-trifluoromethylbenzenesulfonate 2,4
-Nitrobenzyl derivatives such as dinitrobenzyl,
(E) Pyrogallol methanesulfonate (pyrogallol trimesylate), pyrogallol benzenesulfonate, pyrogallol p-toluenesulfonate, pyrogallol p-methoxybenzenesulfonate, pyrogallol mesitylenesulfonate, pyrogallol Benzyl sulfonate, alkyl gallate methane sulfonate, alkyl gallate benzene sulfonate, alkyl gallate p-toluene sulfonate, alkyl gallate p-methoxybenzene sulfonate, alkyl gallate Examples include polyhydroxy compounds such as mesitylene sulfonate, benzyl sulfonate of alkyl gallate, and aliphatic or aromatic sulfonates. Rukoto can. The alkyl group in the alkyl gallate is preferably an alkyl group having 1 to 15 carbon atoms, particularly an octyl group and a lauryl group.

Further, (f) the formula ^{R 4 -I + -R 5 X -} (V) ( wherein, ^{R 4} and ^{R 5,} aryl group, an aryl group having a substituent, a respectively identical X ^- may be AsF ^- ₆ , PF ^- ₆ , BF ^- ₄ , Sb.
_{^{F - 6, CF 3 SO -}} 3 of either) or the general formula

[Chemical 7] (VI) (In the formula, R ⁶ , R ⁷ and R ⁸ are an aryl group and an aryl group having a substituent, and they may be the same or different, and X ⁻ is AsF ^- ₆ and PF ^- _6. , BF ^- ₄ , S
bF ^- _6, CF ₃ SO ^- either a) or onium salt-based acid generator represented by _3, (g) the formula

[Chemical 8] (VII) (In the formula, R ⁹ and R ¹⁰ are an aryl group or an aryl group having a substituent and may be the same or different. R ¹¹ ,
R ¹² is a hydrogen atom, a lower alkyl group, a hydroxyl group or an aryl group and may be the same or different. A benzointosylate-based acid generator represented by the formula (n is 0 or 1) can also be used.

Examples of the onium salt represented by the above general formula (V) or (VI) include the following compounds.

[0020]

[Chemical 9] (VIII) Diphenyliodonium tetrafluoroborate

[0021]

[Chemical 10] (IX) Diphenyliodonium hexafluorophosphate

[0022]

[Chemical 11] (X) Diphenyliodonium hexafluoroantimonate

[0023]

[Chemical 12] (XI) Diphenyliodonium trifluoromethanesulfonate

[0024]

[Chemical 13] (XII) (4-Methoxyphenyl) phenyliodonium hexafluoroantimonate

[0025]

[Chemical 14] (XIII) (4-Methoxyphenyl) phenyliodonium trifluoromethanesulfonate

[0026]

[Chemical 15] (XIV) Bis (p-tert-butylphenyl) iodonium tetrafluoroborate

[0027]

[Chemical 16] (XV) Bis (p-tert-butylphenyl) iodonium hexafluorophosphate

[0028]

[Chemical 17] (XVI) Bis (p-tert-butylphenyl) iodonium hexafluoroantimonate

[0029]

[Chemical 18] (XVII) Bis (p-tert-butylphenyl) iodonium trifluoromethanesulfonate

[0030]

[Chemical 19] (XVIII) Triphenylsulfonium hexafluorophosphate

[0031]

[Chemical 20] (XIX) Triphenylsulfonium hexafluoroantimonate

[0032]

[Chemical 21] (XX) Triphenylsulfonium trifluoromethanesulfonate

[0033]

[Chemical formula 22] (XXI) (4-Methoxyphenyl) diphenylsulfonium hexafluoroantimonate

[0034]

[Chemical formula 23] (XXII) (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate

[0035]

[Chemical formula 24] (XXIII) (4-Methylphenyl) diphenylsulfonium trifluoromethanesulfonate

[0036]

[Chemical 25] (XXIV) Bis (4-methylphenyl) phenylsulfonium trifluoromethanesulfonate

[0037]

[Chemical formula 26] (XXV) (2,4,6-Trimethylphenyl) diphenylsulfonium trifluoromethanesulfonate

[0038]

[Chemical 27] (XXVI) (4-tert-butyl-phenyl) diphenylsulfonium trifluoromethanesulfonate

[0039]

[Chemical 28] (XXVII) Tris (4-methylphenyl) sulfonium trifluoromethanesulfonate

[0040]

[Chemical 29] (XXVIII) Diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate

[0041]

[Chemical 30] (XXIX) Diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate

Of the above-mentioned onium salts, onium salts having trifluoromethanesulfonate as an anion are preferable because they do not contain atoms used as a diffusing agent such as phosphorus, boron and antimony used in the production of semiconductor devices.

The following compounds may be mentioned as examples of the benzointosylate-based acid generator represented by the general formula (VII).

[0044]

[Chemical 31] (XXX)

[0045]

[Chemical 32] (XXXI)

[0046]

[Chemical 33] (XXXII)

[0047]

[Chemical 34] (XXXIII)

[0048]

[Chemical 35] (XXXIV)

These acid generators may be used alone or in combination of two or more. Among the above-mentioned acid generators, those suitable for a resist for excimer laser are (a) bissulfonyldiazomethanes, especially bis (cyclohexylsulfonyl) diazomethane or bis (2,4-dimethylphenylsulfonyl) diazomethane and (e) Of these, aliphatic or aromatic sulfonic acid esters of the polyhydroxy compound, especially pyrogallol trimesylate, and a mixture of these acid generators is particularly preferable because high sensitivity can be achieved.

Further, as the electron beam resist-based acid generator, (d) a nitrobenzyl derivative, particularly 2,6-dinitrobenzyl p-toluenesulfonate, and (e) an aliphatic or aromatic polyhydroxy compound are used. Sulfonates, particularly pyrogallol trimesylate, (f) onium salt-based acid generators, especially bis (p-tert-butylphenyl) iodonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, and (g) benzointosylate A system acid generator is preferred. The amount of the acid generator, 20 parts by weight with respect to the positive resist base resin for 100 parts by weight of component,
The range of 2 to 10 parts by weight is preferably selected. If the amount of the acid generator is less than 1 part by weight , the effect will be insufficient.
When more than 0 parts by weight, on the hardly dissolved in a solvent, miscibility with the <br/> resin component is deteriorated.

The positive resist composition using the base resin of the present invention is further excellent in sensitivity, resolution, cross-sectional shape of resist pattern, and stability after storage after exposure by containing an organic carboxylic acid. Along with
A resist that gives a resist pattern having a good cross-sectional shape can be used for various substrates.

As the organic carboxylic acid, any of saturated or unsaturated aliphatic carboxylic acid, alicyclic carboxylic acid, oxycarboxylic acid, alkoxycarboxylic acid, ketocarboxylic acid, aromatic carboxylic acid and the like can be used without any particular limitation. .
Examples of such an organic carboxylic acid include mono- or polyvalent aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid. , 1-Cyclohexanedicarboxylic acid, 1,2-Cyclohexanedicarboxylic acid, 1,3
-Cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, alicyclic carboxylic acid such as 1,1-cyclohexyldiacetic acid, acrylic acid, crotonic acid, isocrotonic acid, 3-butenoic acid, methacrylic acid, 4-pentenoic acid, Unsaturated aliphatic carboxylic acids such as propiolic acid, 2-butyric acid, maleic acid, fumaric acid and acetylenecarboxylic acid, oxycarboxylic acids such as oxyacetic acid, alkoxycarboxylic acids such as methoxyacetic acid and ethoxyacetic acid, and ketocarboxylic acids such as pyruvic acid. Acid and general formula

[Chemical 36] (XXXV) [In the formula, R ¹³ and R ¹⁴ each independently represent a hydrogen atom, a hydroxyl group, a nitro group, a carboxyl group, or a vinyl group (provided that both R ¹³ and R ¹⁴ are hydrogen atoms)]. And the general formula

[Chemical 37] An aromatic carboxylic acid represented by (XXXVI) (wherein n represents 0 or an integer of 1 to 10) and the like can be mentioned, and in particular, alicyclic carboxylic acid, unsaturated aliphatic carboxylic acid, and aromatic Group carboxylic acids are preferred.

Examples of the aromatic carboxylic acid represented by the above general formula (XXXV) include p-hydroxybenzoic acid, o-hydroxybenzoic acid, 2-hydroxy-3-nitrobenzoic acid, 3,5-dinitrobenzoic acid, 2-nitrobenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid,
3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2-vinylbenzoic acid, 4-vinylbenzoic acid,
Examples thereof include phthalic acid, terephthalic acid and isophthalic acid, and benzoic acid having a substituent at the o-position, such as o-hydroxybenzoic acid, o-nitrobenzoic acid and phthalic acid are particularly preferable.

As the aromatic carboxylic acid represented by the general formula (XXXVI), it is possible to use only those in which n in the formula is single or a combination of different ones, but in practice, SAX (trade name, manufactured by Mitsui Toatsu Chemicals, Inc.), which is commercially available as a phenol compound, is preferable.

The above general formulas (XXXV) and (XXXV)
The aromatic carboxylic acids represented by I) may be used alone or in combination of two or more. The composition of these aromatic carboxylic acids makes it possible to form a resist pattern having a good cross-sectional shape, and has excellent stability over time after exposure after exposure, which is related to the length of time until the heat treatment performed after exposure. And a good profile shape can be formed. In particular, the aromatic carboxylic acid represented by the general formula (XXXVI) is suitable because it can form a rectangular cross section.

The compounding amount of this organic carboxylic acid is
0.01 to 1 relative to the total amount of material resin and acid generatorweight
%, Preferably 0.05 to 0.5weightUsed in the range of
Be done. The amount of organic carboxylic acid is 0.01weightLess than%
Does not provide a resist pattern with a good cross-sectional shape, and
1weight% Is not preferable because the developability is deteriorated.
Yes.

The positive resist composition in which the acid generator and the organic carboxylic acid are added to the base resin of the present invention further prevents unnecessary diffusion of the acid generated by the irradiation of radiation and is faithful to the mask pattern. resist pattern can be formed, and the resolution, in order to increase the引置-out stability over time, 0.01 to 1 wt% based on the amine base resin, thereby preferably contained in the range of 0.05 to 0.5 wt% be able to. As this amine, an aliphatic amine, an aromatic amine, a heterocyclic amine, or the like is used. Examples of the aliphatic amine include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, isopropylamine and the like. Examples of aromatic amines include benzylamine, aniline, N-methylaniline, N, N-dimethylaniline, o-methylaniline, m-methylaniline, p-methylaniline, N, N
-Diethylaniline, diphenylamine, di-p-tolylamine and the like can be mentioned. Further, as the heterocyclic amine, for example, pyridine, o-methylpyridine,
o-ethylpyridine, 2,3-dimethylpyridine, 4-
Mention may be made of ethyl-2-methylpyridine, 3-ethyl-4-methylpyridine and the like. Among these, particularly strongly basic and low-boiling amines, for example, aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine and triethylamine are preferable. These may be used alone or in combination of two or more.

The chemically amplified positive resist composition using the base resin of the present invention contains an N, N-dialkylcarboxylic acid amide in addition to the above-mentioned components to form an isolated resist pattern. Can be improved. The content of the N, N-dialkylcarboxylic acid amide is preferably in the range of 0.1 to 5% by weight based on the base resin. The N, N-dialkylcarboxylic acid amide is preferably an N, N-dialkyl group-substituted lower carboxylic acid amide, for example, N, N-dimethylformamide or N, N-dimethylacetamide. These may be used alone or in combination of two or more.

In the chemically amplified positive resist composition using the base resin of the present invention, it is preferable to further add a light absorber. Examples of this light absorbent include 1- [1
-(4-Hydroxyphenyl) isopropyl] -4-
Naphthoquinone-1,2-diazide-of polyphenols such as [1,1-bis (4-hydroxyphenyl) ethyl] benzene and bis (4-hydroxy-3,5-dimethylphenyl) -3,4-dihydroxyphenylmethane 5
-Sulfonic acid ester, benzophenone and the like are used. By adding these light absorbers, the effect of improving the sensitivity and resolution can be obtained, and the influence of standing waves can be suppressed to give a rectangular resist pattern whose cross-sectional shape is not wavy. The amount of the light absorber blended is 30% by weight based on the total amount of the base resin and the acid generator.
A range not exceeding 10 % by weight , preferably 0.5 to 15% by weight . If the blending amount exceeds 30% by weight , the profile shape becomes worse.

The chemically amplified positive resist composition containing each of the above components is preferably used in the form of a solution dissolved in a solvent for its use. Examples of such a solvent include ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone; ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, and diethylene glycol monoacetate. Polyhydric alcohols and their derivatives such as propylene glycol or dipropylene glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether; cyclic ethers such as dioxane; and methyl lactate, lactic acid Ethyl, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate
Mention may be made of esters such as ethyl ethoxypropionate. These may be used alone or in combination of two or more.

At this time, if desired, an additive miscible with the positive resist composition, for example, an additional resin for improving the performance of the resist film, a plasticizer, a stabilizer, a colorant, a surfactant, etc. The conventional one can be added and contained.

The above chemically amplified positive resist composition comprises
A substrate which is dissolved in a solvent and is provided with an insulating film such as a silicon wafer, a silicon nitride film (SiN) or BPSG using a spinner or the like, titanium nitride (Ti
N), Al-Si-Cu, tungsten, etc. are applied to a substrate provided with a metal film and dried to form a photosensitive layer, and then a reduction projection exposure device or the like is used to perform deep-UV.
Light or excimer laser light is radiated through a desired mask pattern or is drawn with an electron beam, and a developing solution, for example, 1
By developing using an alkaline aqueous solution such as a 10 wt % tetramethylammonium hydroxide aqueous solution, a good resist pattern faithful to the mask pattern is formed. Thus, by using the base resin of the present invention, an excellent resist pattern can be formed without depending on various substrates.

[0063]

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

Reference Example 1 Weight average molecular weight 13,000, molecular weight distribution (Mw / M
n) 120 g of poly (hydroxystyrene) of 1.5 was dissolved in 680 g of N, N-dimethylacetamide and di-tert-butyl-dicarbonate 8 was added to the solution.
After adding 5.0 g and stirring to dissolve completely,
59 g of triethylamine was added dropwise over about 15 minutes.
After completion of dropping, the mixture was stirred for about 3 hours as it was. Then, 20 times the amount of pure water was added to the obtained solution, and the hydroxyl group
Poly (hydroxystyrene) substituted with ert-butoxycarbonyloxy groups was deposited. The precipitate was washed with pure water, dehydrated, and dried to give poly (hydroxystyrene) in which 39% of hydroxyl groups were substituted with tert-butoxycarbonyloxy groups [ weight average molecular weight 13,000.
0, molecular weight distribution (Mw / Mn) 1.5], 150 g was obtained.

Reference Example 2 Weight average molecular weight 13,000, molecular weight distribution (Mw / M
n) 120 g of poly (hydroxystyrene) of 1.5 was dissolved in 680 g of N, N-dimethylacetamide, and 42.3 g of 1-chloro-1-ethoxyethane was dissolved in this solution.
Was added and dissolved completely with stirring, and then 78.8 g of triethylamine was added dropwise over about 30 minutes. After completion of dropping, the mixture was stirred for about 3 hours as it was. Next, 20 times the amount of pure water was added to the resulting solution to precipitate poly (hydroxystyrene) in which the hydroxyl groups were replaced by 1-ethoxyethoxy groups. By washing the precipitate with pure water, dehydration, and drying, poly (hydroxystyrene) in which 39% of hydroxyl groups are substituted with 1-ethoxyethoxy groups [ weight average molecular weight 13,000, molecular weight distribution (Mw / Mn) 1.
5] 130 g was obtained.

Reference Example 3 Poly (hydroxystyrene) in Reference Example 1 had a weight average molecular weight of 13,000 and a molecular weight distribution (Mw / Mn) of 4.
In the same manner as in Reference Example 1 except that poly (hydroxystyrene) of 0 was used, poly (hydroxystyrene) in which 39% of hydroxyl groups were substituted with tert-butoxycarbonyloxy groups [ weight average molecular weight 13,000, molecular weight Distribution (Mw / Mn) 4.0] 150 g was obtained.

Reference Example 4 Poly (hydroxystyrene) in Reference Example 2 was used in a weight average molecular weight of 13,000 and a molecular weight distribution (Mw / Mn) of 4.
In the same manner as in Reference Example 2 except that poly (hydroxystyrene) of 0 was used, poly (hydroxystyrene) in which 39% of hydroxyl groups were substituted with 1-ethoxyethoxy groups [ weight average molecular weight: 13, 000, molecular weight distribution (Mw / Mn)
4.0] 130 g was obtained.

Example 1 3 g of poly (hydroxystyrene) obtained in Reference Example 1 and 7 g of poly (hydroxystyrene) obtained in Reference Example 2,
Bis (cyclohexylsulfonyl) diazomethane 0.4
g, bis (2,4-dimethylphenylsulfonyl) diazomethane 0.1 g, pyrogallol trimesylate 0.2
g, salicylic acid 0.02 g and benzophenone 0.1 g
Was dissolved in 45 g of propylene glycol monomethyl ether acetate, and then triethylamine 0.0
3 g and 0.5 g of N, N-dimethylacetamide were added and dissolved, and the resulting solution was filtered through a membrane filter having a pore size of 0.2 μm to prepare a positive resist coating solution.

Next, the prepared coating solution was applied onto a silicon wafer using a spinner and dried on a hot plate at 80 ° C. for 90 seconds to obtain a resist film having a thickness of 0.7 μm. Reduction projection exposure apparatus NSR-2005E on this film
X8A (manufactured by Nikon Corporation) was added with a dose amount of 1 mJ for exposure, followed by heating at 105 ° C. for 90 seconds, and then development treatment with a 2.38 wt % tetramethylammonium hydroxide aqueous solution at 23 ° C. for 65 seconds, 30 It was washed with water for 2 seconds and dried to form a resist pattern. The cross section of the formed resist pattern was a good rectangular shape with no influence of standing waves, and a line-and-space pattern of 0.21 μm was formed. In addition, the minimum exposure amount at which a large-area resist pattern that can be visually confirmed and the surface of the substrate is exposed was measured as the sensitivity, and as a result, 11 m
It was J / cm ² . Furthermore, the heat resistance of the formed resist pattern (the temperature at which a flow caused by heat occurs) was examined, and it was 135 ° C. 0.25μ as the depth of focus
The maximum width (μm) of the focal point at which a line-and-space pattern of m was formed 1: 1 was 2.0 μm. When this resist solution was stored in a brown bottle at 25 ° C. and its storage stability was examined, no foreign matter was generated for 6 months.

Further, as the stability over time with leaving, a resist pattern is formed in the same manner as described above, and a 0.25 μm line-and-space pattern having a vertical side surface and a favorable profile is formed. From exposure to post-exposure heat treatment. It was 90 minutes when the time until was measured.

Comparative Example 1 3 g of poly (hydroxystyrene) obtained in Reference Example 3 and 7 g of poly (hydroxystyrene) obtained in Reference Example 4,
Bis (cyclohexylsulfonyl) diazomethane 0.7
g, and 0.05 g of salicylic acid were dissolved in 45 g of propylene glycol monomethyl ether acetate, and then 0.01 g of triethylamine and 0.2 g of N, N-dimethylacetamide were added and dissolved to obtain a solution. What was filtered with a filter was prepared as a positive resist coating solution.

Then, a resist pattern was formed from the prepared coating liquid in the same manner as in Example 1. The cross section of the formed resist pattern was a good rectangular shape with no influence of standing waves, and a line-and-space pattern of 0.21 μm was formed. In addition, the minimum exposure amount at which a large-area resist pattern that can be visually confirmed and the surface of the substrate is exposed is measured as the sensitivity, and as a result, 15 mJ / cm ²
Met. Further, as a result of examining the heat resistance (temperature at which heat flow occurs) of the formed large-area resist pattern which can be visually confirmed, it was 125 ° C. The maximum width (μm) of the focus at which a line-and-space pattern having a depth of focus of 0.25 μm was formed 1: 1 was 1.6 μm. When this resist solution was stored in a brown bottle at 25 ° C. and its storage stability was examined, no foreign matter was generated for 6 months.

Further, as the stability with respect to storage over time, a resist pattern was formed in the same manner as in Example 1 except that the post-exposure heat treatment was carried out at 110 ° C. for 90 seconds, and the side surface was vertical and a good profile shape of 0. The time from the exposure for forming a 25 μm line-and-space pattern to the post-exposure heat treatment was 60 minutes.

Example 2 A resist pattern was formed in the same manner as in Example 1 except that the substrate in Example 1 was a silicon wafer having a TiN metal film formed thereon. The cross section of the formed resist pattern was a good rectangular shape with no influence of standing waves, and a 0.23 μm line-and-space pattern was formed.

Example 3 A resist pattern was formed in the same manner as in Example 1 except that the substrate in Example 1 was a silicon wafer on which an insulating film of BPSG was formed. The cross section of the formed resist pattern was a good rectangular shape with no influence of standing waves, and a 0.23 μm line-and-space pattern was formed.

[0076]

The base resin for positive resist of the present invention is
It is useful as a resin component of a chemically amplified positive resist composition, and when it is used, it has high sensitivity and high resolution of less than quarter micron, and also has heat resistance, depth of focus characteristics, and stability during storage over time. It is possible to obtain a resist composition and a solution for forming a resist pattern, which have excellent properties and storage stability of the resist solution, and which provide a resist pattern having an excellent profile shape without depending on the substrate.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yohei Sakai 150 Nakamaruko, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Tokyo Ohka Kogyo Co., Ltd. (72) Hisashi Nakayama 150, Nakamaruko, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Tokyo Ohka Kogyo Incorporated (56) Reference JP-A-5-249682 (JP, A) JP-A-5-281745 (JP, A) JP-A-4-219757 (JP, A) JP-A-6-236037 (JP, A) A) JP-A-6-273934 (JP, A) JP-A-6-273935 (JP, A) JP-A-9-90639 (JP, A) JP-A-9-211866 (JP, A) JP-A-8 -123032 (JP, A) JP-A-2-161436 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (2)

(57) [Claims] 1. A general formula: (Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a methyl group or an ethyl group, and R ³ is a lower alkyl group having 1 to 4 carbon atoms); [Chemical 2] Chemically amplified type consisting of a poly (hydroxystyrene) derivative composed of 90 to 40 mol% of a structural unit represented by the formula (1) and having a weight average molecular weight of 8,000 to 25,000 and a molecular weight distribution (Mw / Mn) of 1.5 or less. Base resin for positive resist. 2. A solvent comprising a chemically amplified positive resist composition containing a positive resist base resin for the claim 1, wherein propylene glycol monomethyl ether acetate
A resist pattern forming solution which is dissolved in an agent .