JP3472771B2 - Positive resist composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel positive resist composition, and more specifically, it has high sensitivity and high resolution, and has heat resistance, depth of focus characteristics, stability over time during storage, and resist solution. Chemically amplified type that is sensitive to radiation such as ultraviolet rays, deep ultraviolet rays, excimer lasers such as KrF and ArF, and X-rays and electron beams, which gives a resist pattern with excellent storage stability and excellent profile shape without substrate dependence. Of the positive resist composition.

[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 present inventors have found that, as a base resin component whose solubility in an alkaline aqueous solution is increased by the action of an acid, a specific proportion of hydroxyl groups is replaced with a specific substituent, and a specific weight. By using poly (hydroxystyrene) having average molecular weight and molecular weight distribution and using it in combination with an acid generator containing a specific diazomethane compound, high sensitivity, high resolution, heat resistance, and depth of focus range can be obtained. In addition to excellent characteristics, storage stability over time and storage stability of resist solution, it is possible to form resist patterns with excellent profile shape without substrate dependence. Excimer lasers such as ultraviolet rays, far ultraviolet rays, KrF and ArF, X-rays, It was found that a chemically amplified positive resist composition sensitive to radiation such as electron beam can be obtained, and the present invention has been completed. .

That is, the present invention provides (A) the general formula

[Chemical 6] 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 7] From 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 a positive resist composition containing (B) bis (cyclohexylsulfonyl) diazomethane or bis (2,4-dimethylphenylsulfonyl) diazomethane or an acid generator containing both of them, and (A) ( a ₁ ) 10 to 60 mol% of the structural unit represented by the general formula (I) and 90 to 40 mol% of the structural unit represented by the formula (II), and a weight average molecular weight of 8,000 to 25 ，
000, a poly (hydroxystyrene) derivative having a molecular weight distribution (Mw / Mn) of 1.5 or less (hereinafter referred to as polyhydroxystyrene a ₁ ), and a (a ₂ ) formula

[Chemical 8] The structural unit represented by (III) is 10 to 60 mol%, and the above formula (I
And 40 to 40 mol% of the structural unit represented by I) and has a weight average molecular weight of 8,000 to 25,000.
A base resin composed of a mixture with a poly (hydroxystyrene) derivative having a molecular weight distribution (Mw / Mn) of 1.5 or less (hereinafter referred to as polyhydroxystyrene a ₂ ) and (B) bis (cyclohexylsulfonyl) diazomethane or bis (2) The present invention provides a positive resist composition containing an acid generator containing 4-, 4-dimethylphenylsulfonyl) diazomethane or both.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The base resin used as the component (A) in the positive resist composition of the present invention is 10 to 60%, preferably 20 to 60% of the hydroxyl groups of poly (hydroxystyrene).
50% in the general formula

[Chemical 9] (IV) (in the formula, R ¹ , R ² and R ³ have the same meanings as described above)
A poly (hydroxystyrene) derivative obtained by substituting with a residue represented by the formula (1), which has a weight average molecular weight of 8,000 to 25,000 and a molecular weight distribution (Mw / M
It is necessary to use those whose n) is 1.5 or less. The substitution rate of hydroxyl groups of this poly (hydroxystyrene) is 10
If it is less than 60%, 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.
Practically, 20 to 50% is preferable.

Examples of the substituent of the general formula (IV) include 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 molecular weight distribution is converted to the above-mentioned general formula (IV) 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.

Further, the component (A) is the above-mentioned general formula (I).
The poly (hydroxystyrene) derivative consisting of the structural unit represented by the formula (II) and the structural unit represented by the formula (II), that is, polyhydroxystyrene a ₁ is 10 to 60% of the hydroxyl group.
Is a poly (hydroxystyrene) substituted with a tert-butoxycarbonyloxy group, ie the formula

[Chemical 10] And 10 to 60 mol% of the structural unit represented by (V)
And 40 to 40 mol% of the structural unit represented by I) and has a weight average molecular weight of 8,000 to 25,000.
It can also be used as a mixture with a poly (hydroxystyrene) derivative having a molecular weight distribution (Mw / Mn) of 1.5 or less, that is, polyhydroxystyrene a ₂ . Use of such a base resin is advantageous because a positive resist composition having more excellent resolution, heat resistance and profile shape can be obtained.

This polyhydroxystyrene a₂Is like
IfweightAverage molecular weight 8,000 to 25,000, molecular weight equivalent
Poly (hydroxystyrene) with cloth (Mw / Mn) of 1.5 or less
Hydroxyl group of di-tert-butyl-dicarbonate
Reaction with tert-butoxycarbonyloxy
It is obtained by substituting with a Si group. At this time,
When the substitution rate is less than 10%, the profile profile is excellent.
I can't give you a giste pattern, and this is
If it exceeds 60%, the sensitivity decreases. Good substitution rate of hydroxyl groups
The preferable range is 20 to 50%. Polyhydroxystyrene
Ren a₁And polyhydroxystyrene a₂Mixed with
The mixing ratio of the former is 30 to 90weight%, The latter is
70-10weight%, Preferably 50-80 for the formerweight
%, The latter is 50-20weightIt is preferable to select within the range of
Yes.

The composition of the present invention comprises the above-mentioned base resin and an acid generator, that is, a compound capable of generating an acid upon irradiation with radiation, whereby it has high sensitivity and high resolution. , Shows good storage stability as a solution. The positive resist composition has heat resistance, depth of focus characteristics,
It provides a resist pattern having a good profile shape that is excellent in stability over time during deposition and has no substrate dependence.

Next, the acid generator used as the component (B) of the composition of the present invention contains bis (cyclohexylsulfonyl) diazomethane or bis (2,4-dimethylphenylsulfonyl) diazomethane or a mixture of both. Is used. The amount of the acid generator compounded is
A range of 1 to 20 parts by weight , preferably 2 to 10 parts by weight is selected with respect to 100 parts by weight of the base resin component. 1 acid generator
The effect is insufficient with less than 20 parts by weight.
If it exceeds the amount, it becomes difficult to dissolve in the solvent and the miscibility with the resin component deteriorates.

The positive resist composition of the present invention may further contain an organic carboxylic acid as the component (C), if desired. This makes it possible to obtain a resist which has excellent sensitivity, resolution, cross-sectional shape of the resist pattern, and stability over time after being placed after exposure, and which gives a resist pattern having a good cross-sectional shape to various substrates.

As such an 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, with particular limitation. There is no. As such an organic carboxylic acid, for example,
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, adipic acid, 1,1-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 Acid, 4
-Pentenoic acid, propiolic acid, 2-butyric acid, maleic acid, fumaric acid, unsaturated aliphatic carboxylic acids such as acetylene carboxylic acid, oxycarboxylic acids such as oxyacetic acid,
Alkoxycarboxylic acids such as methoxyacetic acid and ethoxyacetic acid, ketocarboxylic acids such as pyruvic acid and general formulas

[Chemical 11] (VI) [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 R ¹³ and R ¹⁴ are both hydrogen atoms)]. And the general formula

[Chemical 12] (VII) (In the formula, n represents 0 or an integer of 1 to 10) and the like can be mentioned, but 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 (VI) 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-Dihydroxy Benzoic acid, 3,4
-Dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2-vinylbenzoic acid, 4-vinylbenzoic acid, phthalic acid, terephthalic acid, isophthalic acid, etc., and particularly benzo having a substituent at the o-position Acid, eg o-
Hydroxybenzoic acid, o-nitrobenzoic acid, phthalic acid and the like are preferable.

As the aromatic carboxylic acid represented by the general formula (VII), those in which n in the formula is single or different ones can be used in combination, but in practical use. SAX (trade name, manufactured by Mitsui Toatsu Chemicals, Inc.), which is commercially available as a phenol compound, is preferable.

The aromatic carboxylic acids represented by the above general formulas (VI) and (VII) 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 (VII) is suitable because it can form a rectangular cross section.

The amount of this organic carboxylic acid compounded is
0.01 to 1 relative to the total amount of material resin and acid generatorweight
%, Preferably 0.05 to 0.5weight%Used 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 of the present invention can further prevent unnecessary diffusion of acid generated by irradiation of radiation, can form a resist pattern faithful to a mask pattern, and has high resolution and stability over time. To increase
As the component (D), an amine of 0.01 to
It can be contained in an amount of 1% by weight , preferably 0.05 to 0.5% by weight . As this amine, an aliphatic amine, an aromatic amine, a heterocyclic amine, or the like is used. Examples of this aliphatic amine include methylamine,
Examples thereof include dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine and isopropylamine. Examples of aromatic amines include benzylamine, aniline, N-methylaniline, N, N-dimethylaniline, o-methylaniline, m-methylaniline, p-methylaniline, N, N-diethylaniline, diphenylamine, Examples thereof include di-p-tolylamine. Further, as the heterocyclic amine, for example, pyridine,
o-methylpyridine, o-ethylpyridine, 2,3-dimethylpyridine, 4-ethyl-2-methylpyridine, 3
-Ethyl-4-methylpyridine and the like can be mentioned. 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 positive resist composition of the present invention contains an N, N-dialkylcarboxylic acid amide as the component (E) in addition to the components (A) to (D) described above, so that an isolated resist is obtained. The pattern shape 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 positive resist composition of the present invention, it is preferable to add a light absorber. Examples of the light absorber include 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene and bis (4-hydroxy-3,5-dimethyl). Naphthoquinone-1,2-diazide-5-sulfonic acid esters of polyphenols such as (phenyl) -3,4-dihydroxyphenylmethane, 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.
As the amount of light absorbent, the total does not exceed 30% by weight relative to the weight range of the base resin and the acid generator is preferably selected in the range of 0.5 to 15 wt%. This blend amount is 3
If it exceeds 0% by weight , the profile shape becomes poor.

The 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, dipropylene glycol or dipropylene glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether, etc. Polyhydric alcohols and derivatives thereof; cyclic ethers such as dioxane; and methyl lactate, ethyl lactate, methyl acetate,
Esters such as ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate and ethyl ethoxypropionate can be mentioned. 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-mentioned positive resist composition is dissolved in a solvent and uses a spinner or the like to form, for example, a silicon wafer, a silicon nitride film (SiN), a substrate provided with an insulating film such as BPSG, titanium nitride (TiN), Al. −
After coating a substrate provided with a metal film of Si-Cu, tungsten, etc., and drying it to form a photosensitive layer, a deep-UV light or an excimer laser light is formed into a desired mask pattern by a reduction projection exposure device or the like. Or irradiate through
By drawing with an electron beam and developing with a developing solution, for example, an alkaline aqueous solution such as a 1 to 10 wt % tetramethylammonium hydroxide aqueous solution,
A good resist pattern that is faithful to the mask pattern is formed. Thus, by using the base resin and acid generator of the present invention, an excellent resist pattern can be formed without depending on various substrates.

[0030]

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 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 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 of 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 good profile is formed. 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.

[0043]

INDUSTRIAL APPLICABILITY The positive resist composition of the present invention has high sensitivity and high resolution of not more than quarter micron, and also has heat resistance, focal depth range characteristic, stability during storage for a long time, and preservation of resist solution. It provides a resist pattern with excellent stability, excellent substrate profile, and excellent profile shape.

─────────────────────────────────────────────────── ─── 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 Within the corporation (56) References Patent 3416876 (JP, B2) Patent 3226270 (JP, B2) Patent 3073149 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00- 7/18

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] A base material comprising a poly (hydroxystyrene) derivative having a weight average molecular weight of 8,000 to 25,000 and a molecular weight distribution (Mw / Mn) of 1.5 or less. A positive resist composition comprising a resin and (B) bis (cyclohexylsulfonyl) diazomethane or bis (2,4-dimethylphenylsulfonyl) diazomethane, or an acid generator containing both. 2. (A) (a ₁ ) 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 4] And a poly (hydroxystyrene) derivative having a weight average molecular weight of 8,000 to 25,000 and a molecular weight distribution (Mw / Mn) of 1.5 or less. ₂ ) Formula [Chemical formula 5] Composed of 10 to 60 mol% of the structural unit represented by and 90 to 40 mol% of the structural unit represented by Chemical formula 4,
And a base resin comprising a mixture with a poly (hydroxystyrene) derivative 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 (B) bis (cyclohexylsulfonyl) diazomethane or A positive resist composition comprising an acid generator containing bis (2,4-dimethylphenylsulfonyl) diazomethane or both.