JP2003005370A - Pattern forming method and method for producing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of forming a high resolution negative type pattern. SOLUTION: In the pattern forming method using a radiation sensitive composition containing a copolymer having a hydroxycarboxylic acid structure moiety and a compound which generates an acid when irradiated with radiation, when the mole fraction of the hydroxycarboxylic acid structure moiety at the time when the velocity of dissolution of the copolymer in an aqueous alkali solution having a concentration of b% becomes 10 nm/sec is represented by a%, the mole fraction of the hydroxycarboxylic acid structure of the copolymer in the radiation sensitive composition is adjusted to the range from (a+5)% to (a+20)%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method used in a microfabrication technique in a manufacturing process of semiconductor devices and the like, and a semiconductor device manufacturing method using the pattern forming method.

[0002]

2. Description of the Related Art A photolithography technique for forming a fine pattern of a micron or submicron unit in an electronic device such as a semiconductor has played a central role in a mass production fine processing technique. Recent demands for higher integration and higher density of semiconductor devices are:
Many advances have been made in microfabrication technology. In particular, as the minimum processing dimension approaches the exposure wavelength, photolithography technology using g-line (436 nm) and i-line (365 nm) of high-pressure mercury lamp to KrF excimer laser (248 nm) and light source of shorter wavelength is developed. It has been. In response to these changes in the exposure wavelength, photoresist materials have been developed corresponding to the respective wavelengths. Conventionally, photoresists suitable for these wavelengths have different photosensitizers or photosensitivity mechanisms, but in both cases, aqueous alkali development utilizing the aqueous alkali solubility of a resin or polymer material having a phenol structure has been industrially utilized. It was These resins and polymeric materials inevitably contain many aromatic rings, and this was also a chemical structural element that enhances the etching resistance in the dry etching process after forming the resist pattern.

A negative resist using such a resin having a phenol structure is disclosed in JP-A-62-1640.
No. 45-1653 and the cross-linking type described in Japanese Patent Laid-Open No.
There is a dissolution inhibiting type described in JP-A-59-59. In any case, it is possible to form a submicron fine pattern without swelling.

In recent years, ArF has been used as photolithography for a region having a minimum feature size smaller than 0.25 micron.
Expectations for photolithography using an excimer laser (193 nm) as a light source are increasing. However, this wavelength corresponds to the maximum absorption by the aromatic ring, and in the conventional photoresist material having a phenolic structure as a main component which has been industrially used, the exposure latent image can be formed only on the extreme surface of the photoresist film. It has been difficult to form a fine resist pattern by aqueous alkaline development.

On the other hand, various resist materials having high transmittance in this wavelength region and high dry etching resistance have been proposed. ArF excimer laser wavelength 19
Use of an adamantane skeleton as a chemical structure that is transparent in the deep ultraviolet region including 3 nm and can impart dry etching resistance to a resist material in place of an aromatic ring is disclosed in JP-A-4-396.
In Japanese Patent Laid-Open No. 65-26512 and Japanese Patent Laid-Open No. 5-265212, use of a norbornane skeleton is similarly disclosed in Japanese Patent Laid-Open Nos. 5-80515 and 5-257284.
In addition to these structures, tricyclodecanyl group, etc.,
The fact that alicyclic structures are generally effective is disclosed in JP-A-7-2823.
No. 7 and Japanese Patent Laid-Open No. 8-259626.

A polymer having a transparent chemical structure in the far ultraviolet region including the wavelength of 193 nm of ArF excimer laser,
Regarding the resist material which can be developed with an aqueous alkali, JP-A-4-39665 and JP-A-4-1843 are available.
45, JP-A-4-226461, JP-A-5
As disclosed in Japanese Unexamined Patent Publication (Kokai) No.-80515, it has been attempted to utilize a carboxylic acid structure of acrylic acid or methacrylic acid. In these, the aqueous alkali-solubility of the portion which is dissolved in the developer in the aqueous alkali development is based on the carboxylic acid structure of acrylic acid or methacrylic acid. Further, JP-A-8-259626 discloses a polymer compound in which a carboxylic acid group is added to the alicyclic structure introduced into the methacrylic acid ester side chain.

In the phenol structure conventionally used as an alkali-soluble group, pKa = 10.0 (phenol), while in these carboxylic acid structures, pKa = 1.
It has a low value of Ka = 4.8 (acetic acid) and high acidity. Therefore, when using them as the alkali-soluble group of the base resin, generally, at the same mole fraction, the resin having a carboxylic acid structure has a higher dissolution rate in aqueous alkali,
Further, the resin having a carboxylic acid structure is soluble even in a low-concentration alkaline developing solution in which the resin having a phenol structure is insoluble.

When a resin having a carboxylic acid as described above is used and a cross-linking agent as disclosed in JP-A-62-164045 is used, the cross-linked portion, that is, the hardened portion also has a high acidity. No consideration was given to the swelling and swelling of the alkaline developer due to the remaining part of the carboxylic acid. In addition, Japanese Patent Laid-Open No. 4-16
When a compound having a dissolution inhibiting action is formed by an acid generated by exposure, which is seen in Japanese Patent No. 5359, a resin having a carboxylic acid does not have a dissolution contrast,
No consideration was given to the fact that it would not be a negative resist.

On the other hand, as a method of forming a non-swelling negative pattern using a resin having a carboxylic acid structure, a γ- or δ-hydroxycarboxylic acid structure can be formed by γ-lactone or A method utilizing the change to a δ-lactone structure is found in JP-A-11-109627. Further, an acrylate polymer and a methacrylate polymer having the hydroxycarboxylic acid structure in the side chain are reported in Japanese Patent Application No. 11-356969 as compounds exhibiting high resolution.

[0010]

In the above-mentioned polymer having a γ-hydroxycarboxylic acid structure or a δ-hydroxycarboxylic acid structure in its side chain, an ester is efficiently esterified in the molecule with an acid catalyst to form a 5-membered ring or Form a 6-membered lactone. As a result, the number of carboxylic acids is greatly reduced. Therefore, unlike the crosslinking reaction in which the reaction takes place between the molecules and the number of carboxylic acids hardly changes between the exposed and unexposed areas, it is difficult for the developing solution to penetrate into the exposed and insolubilized areas, and the pattern after development is not easily generated. Can be suppressed. However, in the fine pattern formation of 0.12 micron level required for pattern formation with ArF excimer laser, even in the system in which the carboxylic acid decreases as described above, the permeation of the developing solution cannot be suppressed and the swelling occurs. It was not possible to obtain a pattern having a good shape, because the resist film remained between the lines of the pattern.

The first object of the present invention is to eliminate the causes of resolution deterioration such as the swelling due to the penetration of the developing solution and the resist film remaining between the lines of the pattern as described above, and it is possible to form a high resolution pattern. Another object of the present invention is to provide a negative pattern forming method. A second object of the present invention is to provide a method of manufacturing a semiconductor device using such a pattern forming method.

[0012]

In order to achieve the above-mentioned first object, the pattern forming method of the present invention comprises a step of forming a coating film of a radiation-sensitive composition on a substrate, and a pattern-like coating on the coating film. The step of irradiating the substrate with radiation, the step of heating the substrate after the irradiation of the radiation, and the step of exposing the coating film to an alkaline aqueous solution with a concentration of b% after the substrate is heated to remove the non-irradiated portion. The composition has the general formula (1)

[0013]

[Chemical 3] (However, R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and A represents an alicyclic hydrocarbon group together with carbon atoms C ¹ and C ^2. Represents a plurality of atoms necessary for constituting, x and y are 0, 1 or 2, respectively, and satisfy the condition of x + y = 1 or 2, and n represents a positive integer) A general formula (2) containing a polymer having a structure and a compound that generates an acid upon irradiation with radiation and having a dissolution rate of 10 nm / s in an aqueous alkali solution having a concentration of b% ( When the mole fraction of the structure represented by 1) is a%, the polymer in the radiation-sensitive composition has a mole fraction of the structure represented by the general formula (1) of (a + 5)% or more, (a + 20). % Or less (however, when (a + 20)% exceeds 100%, it is 100% or less. In which it was to be with.

In order to achieve the above second object,
The method for manufacturing a semiconductor device of the present invention has a step of forming a resist pattern on a substrate, and the resist pattern is formed by the above-mentioned pattern forming method.

After forming a coating film of the radiation-sensitive composition on the substrate by the above pattern forming method, the substrate is heated to 100 ° C.
It is preferable to heat to some extent. This is because it is more sensitive if the coating film does not contain water.

Examples of the ring structure composed of A, C ¹ and C ² include a monocyclic hydrocarbon group, a condensed polycyclic hydrocarbon group, a crosslinked cyclic hydrocarbon group and a spiro hydrocarbon group. Examples of the polymer having the structure represented by the general formula (1) include γ-
Alternatively, a polymer having a δ-hydroxycarboxylic acid structure is preferable.

Further, the structure represented by the general formula (1) of the above polymer is represented by the following general formula (2).

[0018]

[Chemical 4] (In the formula, R ⁴ represents a hydrogen atom or a methyl group, and n
Represents a positive integer). This is because it is particularly effective in terms of resolution performance, dry etching resistance, and storage stability. In the formula, R ⁴ is a hydrogen atom or a methyl group, but it is preferable that the polarity in the vicinity of the main chain of the polymer is high, and a hydrogen atom is more preferable than a methyl group. Here, the polymer is a polymer in a broad sense including a copolymer.

When the above-mentioned fine pattern formation is carried out using a polymer having a mole fraction of general formula (1) of less than a%, the polymer is insoluble in an alkali developing solution having a concentration of b%. The pattern cannot be formed because it does not have sufficient solubility. Further, the mole fraction of the general formula (1) is a% or more, (a
When a polymer of less than +5)% is used, for example, the resist film remains between the lines of the line and space pattern.
A schematic view of the resist cross-sectional shape at that time is shown in FIG. Further, when a polymer having a mole fraction of the general formula (1) of more than (a + 20)% is used, swelling of the line and space pattern occurs. A schematic view of the resist cross-sectional shape at that time is shown in FIG. On the other hand, when a polymer having a molar fraction of the general formula (1) of (a + 5)% or more and (a + 20)% or less is used, a good pattern can be obtained. A schematic diagram of the cross-sectional shape of the line and space pattern at that time is shown in FIG.

Using an ArF excimer laser, 0.12
When pattern formation on the micron level is performed, the exposure profile is considerably deteriorated even if a super-resolution exposure technique such as a Levenson type phase shift mask is used. For example, the light intensity at the unexposed portion of the line and space pattern does not become completely 0, and a slight amount of light strikes it. Therefore, even between the lines of the pattern, the carboxylic acid is slightly reduced due to the acid-catalyzed reaction. As a result, the polymer having a molar fraction of the general formula (1) of less than (a + 5)% becomes insoluble in an alkaline aqueous solution having a concentration of b%, and the resist film remains between the lines of the pattern. On the contrary, in the exposed portion, the light intensity is weaker in the portion slightly deviated from the center of the pattern than in the central portion of the pattern. Therefore, the carboxylic acid is not sufficiently reduced by the acid-catalyzed reaction. As a result, the molar fraction of the general formula (1) was (a + 20).
% Of the polymer, a large amount of unreacted carboxylic acid remains at a position slightly deviated from the center of the pattern, so that the permeation of the alkali developer having a concentration of b% cannot be suppressed and the polymer swells. From these facts, swelling due to permeation of an alkali developing solution having a concentration of b% can be achieved by using a polymer having a molar fraction of general formula (1) in the range of (a + 5)% or more and (a + 20)% or less. A high-resolution pattern can be formed without causing deterioration of resolution such as a resist film remaining between the lines of the pattern. Furthermore, the molar fraction of the general formula (1) is (a + 5)% or more, (a + 1
0)% polymer is used,
It is more preferable not only in forming a high-resolution pattern, but also in terms of high sensitivity.

In the above polymer used in the present invention,
The constituents other than the structure represented by the general formula (1) are not particularly limited as long as they constitute a copolymer, but methyl acrylate, methyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, acryloyloxy-β, β-dimethyl. -Γ-butyrolactone, acryloyloxyandrosterone, ethyl (α-
Examples thereof include hydroxyethyl) acrylate, a copolymer of maleic anhydride and norbornene, and a copolymer of citraconic anhydride and norbornene. Moreover, you may use these 2 or more types simultaneously. The copolymer of maleic anhydride or citraconic anhydride and norbornene is SEM.
It is effective in terms of resistance and dry etching resistance.

The weight average molecular weight of the above polymer is from 800 to
500,000 is preferable, more preferably 1,000
~ 30,000.

Examples of the compound that generates an acid upon irradiation with radiation (hereinafter referred to as an acid generator) include onium salts such as triphenylsulfonium triflate, dimethylphenylsulfonium triflate, dimethyl-4-hydroxynaphthyl triflate, and N-. Examples thereof include sulfonyloxyimides such as trifluoromethanesulfonyloxynaphthylimide, N-methanesulfonyloxynaphthylimide, N-trifluoromethanesulfonyloxysuccinimide, N-perfluorooctanesulfonyloxysuccinimide, and further sulfonate ester. However, it is not limited to these as long as they generate an acid by irradiation with radiation such as ArF excimer laser. Two or more kinds of these acid generators may be used at the same time. These acid generators are based on the polymer 100 described above.
It is preferably used in the range of 0.1 to 50 parts by weight, and more preferably in the range of 0.5 to 20 parts by weight with respect to parts by weight.

Further, the photosensitive composition of the present invention has a composition for improving resolution, process stability and storage stability.
A basic compound such as benzylpyridine, phenylpyridine, tripentylamine, triethanolamine, or a salt such as tetramethylammonium iodide, tetrapentylammonium chloride, or tetraethylphosphonium iodide may be added. It is desirable to add 0.01 to 100 parts by weight of these basic compounds and salts to the acid generator used.

The radiation used in the present invention includes far-ultraviolet light of 250 nm or less and vacuum ultraviolet light such as ArF excimer laser light. Note that electron beams, EUV, X-rays, etc. can also be used.

When irradiating radiation of a desired pattern in the present invention, vacuum ultraviolet light such as ArF excimer laser light is usually formed into a predetermined pattern through a mask or reticle. At this time, when a super-resolution technique represented by a modified illumination method or a phase shift mask is used, a pattern with higher resolution can be obtained, which is desirable.

The above-mentioned alkaline aqueous solution having a concentration of b% is preferably a tetraalkylammonium hydroxide aqueous solution having 1 to 5 carbon atoms. The concentration of the aqueous alkaline solution is preferably 0.01% to 10%, more preferably 0.04% to 2.4%.

According to the method of manufacturing a semiconductor device of the present invention, a resist pattern is formed as described above, and a substrate or a semiconductor layer is etched based on the resist pattern or ions are implanted to form a semiconductor element. Form. Examples of the etching processing method include dry etching methods such as plasma etching, reactive ion etching, and reactive ion beam etching, and wet etching methods.

As the substrate processed in the method of manufacturing a semiconductor device of the present invention, a silicon dioxide film formed by a CVD method or a thermal oxidation method, an oxide film such as a coatable glass film, or a nitride film such as a silicon nitride film. Is mentioned. Further, aluminum, an alloy thereof, various metal films such as tungsten, and polycrystalline silicon can be used.

Since the elements manufactured by the method for manufacturing a semiconductor device according to the present invention, especially the memory elements, can be formed in a fine pattern, the degree of integration can be increased. Therefore, since the elements can be made small, the number of elements that can be obtained from one wafer is increased, and the yield is improved. Also, the bit cost can be reduced. Therefore, a nonvolatile semiconductor memory device such as a flash memory or a DRAM
Suitable for manufacturing (Dynamic Random Access Memory).

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Example 1 5.0 g of androsterone and 1.5 g of pyridine were dissolved in 200 ml of tetrahydrofuran, and a solution of 1.6 g of acrylic acid chloride in 30 ml of tetrahydrofuran was added dropwise at 0 ° C. After the dropping, the mixture was further stirred at room temperature for 12 hours, and the precipitated pyridine hydrochloride was filtered off.
Add 150 ml of ethyl acetate to the filtrate and add 4 ml with 100 ml of water.
It was washed with water twice. After washing with water, the organic layer was dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to crystallize the residue. This was recrystallized from a mixed solvent of ethanol / tetrahydrofuran to obtain a white compound (3) represented by the following formula.

[0032]

[Chemical 5] The obtained compound (3) (4.0 g) was added to acetic acid (100 ml).
Dissolve in, add 50 ml of hydrogen peroxide and add 12 at 35 ° C.
Stir for hours. After the reaction, the solvent was distilled off under reduced pressure to reduce it to 1
Poured into 000 ml of water. The precipitate was filtered off and dried to obtain an acrylate monomer (4) having a δ-lactone structure represented by the following formula.

[0033]

[Chemical 6] Acrylate monomer (4) synthesized as described above 3.
Dissolve 0 g in 150 ml of tetrahydrofuran,
100 ml of N sodium hydroxide aqueous solution was added and stirred for 3 hours. Aqueous hydrochloric acid solution was gradually added thereto to make it weakly acidic. About 150 ml of ethyl acetate was added to this solution, extraction was performed twice, and the obtained organic layer was washed twice with 100 ml of water. After washing, the organic layer is dried over anhydrous sodium sulfate,
Then, the solvent was distilled off under reduced pressure to reduce the amount, and n-hexane 300 was added.
Poured to ml. The precipitate is filtered off and dried to give an acrylate monomer (5) having a δ-hydroxycarboxylic acid structure.
Got The structure of the obtained monomer was found to be the following structure by various analytical methods.

[0034]

[Chemical 7] and ^{- (4} mol 8.0 × 10), acrylate monomer having a δ- hydroxycarboxylic acid structure (5) 0.302 g
Acrylate monomer having δ-lactone structure (4)
0.072 g ^- a (2.0 × 10 ⁴ mol) was dissolved in tetrahydrofuran 10 ml, it was bubbled with nitrogen for 10 minutes. Then, as a polymerization initiator (2RS, 2'RS)-
Azobis (4-methoxy-2,4-dimethylvaleronitrile) (0.02 g) was added, and polymerization was carried out at 20 ° C. for 10 hours in a nitrogen atmosphere. After polymerization, n-hexane 300m
The solution was poured into 1 to precipitate a polymer, which was filtered and dried to obtain a polymer (6). The structure of the obtained polymer was found from various analytical methods to be an acrylate polymer (6) having a δ-hydroxy acid structure and a mole fraction of 80%. The formula of the acrylate polymer (6) is δ-
Although it is described that the portion 0.8 of the hydroxy acid structure and the portion 0.2 having the δ-lactone structure are copolymerized, the actual structure is an ordinary random copolymer,
It only shows that each ratio is 8 to 2. This also applies to the following polymer formulas.

[0035]

[Chemical 8] When the polystyrene equivalent molecular weight of this polymer was examined by gel permeation chromatography (GPC) in tetrahydrofuran, the weight average molecular weight was 5,400 and the number average molecular weight was 4,500.

As in the above synthesis example, δ- used for polymerization
By controlling the ratio of the acrylate monomer (5) having a hydroxycarboxylic acid structure and the acrylate monomer (4) having a δ-lactone structure, acrylate polymers having a δ-hydroxy acid structure with different mole fractions were synthesized.

The relationship between the dissolution rate and the molar fraction of 0.05% concentration of tetramethylammonium aqueous solution of the coating film of the copolymers containing acrylates having different molar fractions of δ-hydroxy acid structure was investigated. . 100 parts by weight of the above polymer was dissolved in 1200 parts by weight of 1-methoxy-2-propanol, and the above solution was spin-coated on a silicon substrate. After coating, heat treatment at 100 ° C for 2 minutes to obtain a film thickness of 0.3.
A 0 micron film was formed. The dissolution rate was obtained simply by measuring the time until the coated film disappeared in an aqueous solution of tetramethylammonium hydroxide (0.05% by weight), and by simply measuring it and the coated film thickness. For the part where the film was not completely melted, the dissolution rate was determined from the film thickness that decreased during the development time. The results are shown in Fig. 4. According to this, the molar fraction of δ-hydroxycarboxylic acid is 68% and the dissolution rate is 1
It became 0 nm / s, and it was found that it had a sufficient solubility in an alkali developing solution.

Next, with respect to 100 parts by weight of the above copolymer, the acid generator triphenylsulfonium nonaphlate 1 was added.
Parts by weight, 0.2 parts by weight of 4-phenylpyridine are dissolved in 1200 parts by weight of 1-methoxy-2-propanol, and this is filtered using a Teflon (registered trademark) filter having a pore size of 0.20 micron to obtain a resist solution. did.

The above resist solution was spin-coated on a silicon substrate treated with hexamethyldisilazane, and after coating, heat treatment was carried out at 100 ° C. for 2 minutes to form a resist film having a thickness of 0.30 μm. ArF excimer laser stepper (ISI Microstep, NA = 0.60)
Was used to expose the resist film through a Levenson type phase shift mask. After the exposure, post-exposure baking was performed at 100 ° C. for 2 minutes. Development was performed for 30 seconds with an aqueous solution of tetramethylammonium hydroxide (0.05% by weight), followed by rinsing with pure water for 15 seconds.

As a result of forming the line and space pattern, in the case of a resist using a polymer having a δ-hydroxy acid structure mole fraction of less than 68%, the unexposed portion of the resist film was dissolved in a developing solution. No pattern formation was possible. The molar fraction of δ-hydroxy acid structure is 68% or more 73
In the case of a resist using less than 1% of the polymer, the resist film remained between the pattern lines, and the pattern of 0.12 micron or less could not be formed. In the case of a resist using a polymer having a molar fraction of δ-hydroxy acid structure of 73% or more and less than 78%, an exposure amount of 20 mJ / cm ² and a negative type of 0.1.
A 0 micron line and space pattern was obtained. At this time, no swelling of the pattern was observed and no residue was observed between the pattern lines. Further, in the case of a resist using a polymer having a δ-hydroxy acid structure mole fraction of 78% or more and 88% or less, an exposure amount of 25 mJ / cm ² and a negative type of 0.10
A micron line and space pattern was obtained. Although the sensitivity was slightly lowered, no swelling of the pattern was observed and no residue was observed between the pattern lines. In the case of a resist using a polymer having a δ-hydroxy acid structure mole fraction of more than 88%, the pattern swelled and a pattern of 0.12 micron or less could not be formed.

Example 2 According to the synthesis example shown in Example 1, acrylate monomer (5) 0.3 having a δ-hydroxycarboxylic acid structure was prepared.
And ^{- (4} mol 8.0 × 10), methylmethacrylate monomer 0.02 g 02G ^- was polymerized (2.0 × 10 ⁴ mol). The structure of the obtained polymer was found to be a polymer (7) having a δ-hydroxy acid structure with a mole fraction of 80% from various analytical methods.

[0042]

[Chemical 9] The polystyrene conversion molecular weight of this polymer was examined by gel permeation chromatography (GPC). As a result, the weight average molecular weight was 6,000 and the number average molecular weight was 5,100.

As in the above synthesis example, δ- used for polymerization
By controlling the ratio of the acrylate monomer (5) having a hydroxycarboxylic acid structure and the methylmethacrylate monomer, copolymers containing different acrylates having a δ-hydroxy acid structure in different mole fractions were synthesized.

As in Example 1, δ-with different mole fractions
Concentration of coating film of polymer having hydroxy acid structure 0.05
% Dissolution rate in tetramethylammonium aqueous solution and the molar fraction were investigated. Results are shown in FIG. According to this, the dissolution rate becomes 10 nm / s in a tetramethylammonium aqueous solution having a molar fraction of δ-hydroxycarboxylic acid of 27% and a concentration of 0.05%, and has sufficient solubility in an alkali developing solution. I found out.

Next, as in Example 1, a line and space pattern was formed. As a result of using a polymer having a molar fraction of δ-hydroxy acid structure of less than 27%, the resist film in the unexposed portion was not dissolved in a developing solution having a concentration of 0.05%, and a pattern could not be formed. As a result of using a polymer in which the molar fraction of the δ-hydroxy acid structure is 27% or more and less than 32%, a resist film remains between pattern lines.
Patterns of micron or less could not be formed. As a result of using a polymer having a δ-hydroxy acid structure mole fraction of 32% or more and less than 37%, a negative type 0.10 micron line and space pattern was obtained at an exposure dose of 15 mJ / cm ² . At this time, no swelling of the pattern was observed and no residue was observed between the pattern lines. Further, as a result of using a polymer having a δ-hydroxy acid structure mole fraction of 37% or more and 47% or less, a negative type 0.10 micron line and space pattern was obtained at an exposure dose of 20 mJ / cm ² . . Although the sensitivity was slightly lowered, no swelling of the pattern was observed and no residue was observed between the pattern lines. As a result of using a polymer having a δ-hydroxy acid structure mole fraction of more than 47%, the pattern swelled and a pattern of 0.12 micron or less could not be formed.

Example 3 FIG. 6 shows a cross-sectional view of a known MOS (metal-oxide-semiconductor) type transistor. This transistor has a structure in which the drain current flowing between the source electrode 16 and the drain electrode 17 is controlled by the voltage applied to the gate electrode 18. In the figure, 11 is a substrate, 12 is a field oxide film, 13 is a source contact, 14 is a drain contact, 15 is polycrystalline silicon, and 19 is a protective film.

Here, the process of forming such a structure is made up of ten or more processes, which are roughly divided into three groups: a process for forming a field oxide film, a process for forming a gate, and a final process. be able to. Here, the step of forming the field oxide film for the first time (FIG. 7) includes the step of forming a resist pattern on the silicon nitride film. This field oxide film was formed as in the following examples.

By a known method, a 50 nm oxide film 22 is formed on a p-type silicon wafer 21 as shown in FIG. 7A, and a 200 nm silicon nitride film 23 is formed thereon by plasma CVD to form a substrate. To do. A resist pattern 24 of 0.30 micron line is formed on this substrate by the material and the method shown in Embodiment 1 (FIG. 7B). After etching the silicon nitride film 23 by a known method using the resist pattern 24 as a mask (FIG. 7C),
Using this resist as a mask again, boron ion implantation for a channel stopper is performed. After removing the resist (FIG. 7D), 1.2-micron field oxide films 12 and 25 are formed in the element isolation region by selective oxidation using the silicon nitride film 23 as a mask (FIG. 7E).

After that, a gate forming step and a final step were performed according to a known method. After etching the silicon nitride film, the gate is oxidized to grow polycrystalline silicon (FIG. 7F). A resist pattern 27 of 0.10 micron line is formed on this substrate by using the pattern forming method shown in Embodiment 1 (FIG. 7G). Using this resist pattern as a mask, the polycrystalline silicon is etched by a known method to form the gate 28 (FIG. 7 (h)).
The thin oxide film of the source and drain is etched, and then arsenic is diffused into the gate 28 and the source and drain to form an oxide film in the gate, source and drain regions. Gate,
A contact for aluminum wiring to the source and drain is opened, aluminum vapor deposition and patterning are performed, a protective film is further formed, and a pad for bonding is opened. In this way, the MOS type transistor as shown in FIG. 6 is formed.

Here, regarding the MOS type transistor,
In particular, the method for forming the field oxide film has been described, but it goes without saying that the present invention is not limited to this, and can be applied to other semiconductor element manufacturing methods and processes.

Example 4 A semiconductor memory device was manufactured by using the pattern forming method shown in Example 1 or 2. FIG. 8 is a sectional view of the semiconductor device showing the main steps of manufacturing the element. As shown in FIG. 8A, a P-type Si semiconductor 31 is used as a substrate, and an element isolation region 32 is formed on the surface of the substrate by a known element isolation technique.
Next, a word line 33 having a structure in which polycrystalline Si having a thickness of 150 nm and SiO ₂ having a thickness of 200 nm are stacked is formed, and further 150 nm of SiO ₂ is deposited by chemical vapor deposition to form an anisotropic layer. Are processed to form side spacers 34 of SiO _{2 on} the side walls of the word lines. Next, the n diffusion layer 35 is formed by a usual method.

Next, as shown in FIG. 8B, the data line 36 made of polycrystalline Si, refractory metal, metal silicide, or a laminated film of these is formed through a normal process. Next, as shown in FIG. 8C, a storage electrode 38 made of polycrystalline Si is formed through a normal process. After that, Ta ₂ O ₅ , S
i ₃ N ₄ , SiO ₂ , BST, PZT, a ferroelectric film or a composite film of these or the like is deposited to form a capacitor insulating film 39. Subsequently, a low resistance conductor such as polycrystalline Si, a high melting point metal, a high melting point metal silicide or Al, Cu is deposited to form the plate electrode 40. Next, as shown in FIG. 8D, the wiring 41 is formed through a normal process. Next, a memory element was manufactured through a normal wiring forming step and a passivation step. In addition, here, only the typical manufacturing process was described, but other than this, the normal manufacturing process was used. The present invention can be applied even if the order of each step is changed.

Element isolation region 3 in the above element manufacturing process
2 is applied, the pattern forming method shown in the first embodiment is applied to the lithography process including the step of forming the word line 33, the step of forming the side spacer 34, and the step of forming the storage electrode 38. The pattern forming method shown in the second embodiment is applied to the lithography process including the step of forming 36, the step of forming the capacitor insulating film 39, the step of forming the plate electrode 40, and the step of forming the wiring 41.

However, the present invention does not necessarily have to be applied to a step in which pattern formation with a negative resist is unsuitable or a step in which the size of the pattern is large. For example, the present invention is not applied to the conductive hole forming step in the passivation step or the pattern forming in the ion implantation mask forming step.

Next, a pattern formed by lithography will be described. FIG. 9 shows the pattern layout of the memory portion of the pattern of the memory device manufactured in the above process. 42 is a word line, 43 is a data line, 44 is an active region, 45 is a storage electrode, and 46 is a pattern of electrode extraction holes. Also in this example, the pattern formation of Example 1 or 2 of the present invention was used for all except the formation of the 46 electrode lead-out holes shown here. The present invention can be used in the process using the minimum design rule other than the pattern formation shown here.

The element manufactured by using the present invention can reduce the dimension between patterns as compared with the element manufactured by the conventional method. Therefore, an element having the same structure can be made smaller, the number of semiconductor elements that can be manufactured from one wafer is increased, and the yield is improved.

Example 5 In the same manner as in Example 1, except that 1.8 g of methacrylic acid chloride was used instead of 1.6 g of acrylic acid chloride, a methacrylate monomer (8) having a δ-hydroxycarboxylic acid structure was obtained. It was The structure of the obtained monomer was found to be the following structure by various analytical methods.

[0058]

[Chemical 10] According to the polymerization method shown in Example 1, a methacrylate monomer (8) having a δ-hydroxycarboxylic acid structure (8).
And ^{- (4} mol 8.0 × 10), methylmethacrylate monomer 0.02 g 31 g ^- obtained by polymerizing (2.0 × 10 ⁴ mol). The structure of the obtained polymer was found to be a polymer (9) having a δ-hydroxy acid structure with a mole fraction of 80% from various analytical methods.

[0059]

[Chemical 11] When the polystyrene-equivalent molecular weight of this polymer was examined by gel permeation chromatography (GPC), the weight average molecular weight was 5,000 and the number average molecular weight was 4,000.

As in the above synthesis example, δ- used for polymerization
By controlling the ratio of the methacrylate monomer (8) having a hydroxycarboxylic acid structure and the methylmethacrylate monomer, a polymer having a δ-hydroxy acid structure having different mole fractions was synthesized.

As in Example 1, different molar fractions of δ-
Concentration of coating film of polymer having hydroxy acid structure 0.05
% Dissolution rate in tetramethylammonium aqueous solution and the molar fraction were investigated. The results are shown in Fig. 10. According to this, the dissolution rate is 10 nm / s in a tetramethylammonium aqueous solution having a molar fraction of δ-hydroxycarboxylic acid of 48% and a concentration of 0.05%, and has sufficient solubility in an alkali developing solution. I found out.

Next, as in Example 1, a line and space pattern was formed. As a result of using a polymer having a δ-hydroxy acid structure mole fraction of less than 48%, the resist film in the unexposed portion was not dissolved in a developer having a concentration of 0.05%, and a pattern could not be formed. As a result of using a polymer having a molar fraction of the δ-hydroxy acid structure of 48% or more and less than 53%, a resist film remains between the pattern lines.
Patterns of micron or less could not be formed. As a result of using a polymer having a δ-hydroxy acid structure mole fraction of 53% or more and less than 58%, a negative type 0.10 micron line and space pattern was obtained at an exposure dose of 15 mJ / cm ² . At this time, no swelling of the pattern was observed and no residue was observed between the pattern lines. Further, as a result of using a polymer having a δ-hydroxy acid structure mole fraction of 58% or more and 68% or less, a negative type 0.10 micron line and space pattern was obtained at an exposure dose of 20 mJ / cm ² . . Although the sensitivity was slightly lowered, no swelling of the pattern was observed and no residue was observed between the pattern lines. As a result of using a polymer in which the molar fraction of the δ-hydroxy acid structure was more than 68%, the pattern was swollen and a pattern of 0.12 micron or less could not be formed.

[0063]

By controlling the mole fraction of the structure represented by the general formula (1) in the polymer, the resolution such as swelling due to permeation of the developing solution or the resist film remaining between the lines of the pattern can be obtained. It became possible to form a high-resolution pattern without removing the cause of deterioration, and it was possible to manufacture a semiconductor device in which the dimension between patterns was reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a resist pattern when a polymer having a δ-hydroxycarboxylic acid mole fraction of a% or more and less than (a + 5)% is used.

FIG. 2 shows that the molar fraction of δ-hydroxycarboxylic acid is (a +
20) A schematic cross-sectional view of a resist pattern in the case of using more than 20% by weight of polymer.

FIG. 3 shows that the molar fraction of δ-hydroxycarboxylic acid is (a +
5) A schematic cross-sectional view of a resist pattern when a polymer of 5% or more and (a + 20)% or less is used.

FIG. 4 is a dissolution rate of a coating film of a polymer synthesized from a monomer having a δ-hydroxycarboxylic acid structure and a monomer having a δ-lactone structure in a 0.05% tetramethylammonium aqueous solution and δ-hydroxy acid. The characteristic view showing the relationship of the mole fraction of a structure.

FIG. 5: Dissolution rate of a coating film of a polymer synthesized from a monomer having a δ-hydroxycarboxylic acid structure and a methylmethacrylate monomer in a 0.05% tetramethylammonium aqueous solution and the molar content of the δ-hydroxy acid structure. The characteristic view showing the relationship of a rate.

FIG. 6 is a cross-sectional view of a MOS (metal-oxide-semiconductor) type transistor.

FIG. 7 is a diagram showing a method of forming a field oxide film and a silicon gate using the pattern forming method of the present invention.

FIG. 8 is a cross-sectional view of a process of a method of manufacturing a semiconductor memory device using the pattern forming method of the present invention.

FIG. 9 is a pattern layout diagram of a memory section of a typical pattern forming a memory element.

FIG. 10: Dissolution rate and molar ratio of δ-hydroxy acid structure in a 0.05% concentration tetramethylammonium aqueous solution of a coating film of a polymer synthesized from a methacrylate monomer having a δ-hydroxycarboxylic acid structure and a methyl methacrylate monomer. The characteristic view showing the relationship of fractions.

[Explanation of symbols]

1 ... Resist film, 2 ... Resist residual film, 3, 11 ... Substrate,
12, 25 ... Field oxide film, 13 ... Source contact, 14 ... Drain contact, 15 ... Polycrystalline silicon, 16 ... Source electrode, 17 ... Drain electrode, 18 ... Gate electrode, 19 ... Protective film, 21 ... P-type silicon wafer ,
22 ... Oxide film, 23 ... Silicon nitride film, 24 ... Resist pattern, 26 ... Polycrystalline silicon film, 27 ... Resist pattern, 28 ... Gate, 31 ... P-type Si semiconductor substrate, 32 ...
Element isolation regions, 33, 42 ... Word lines, 34 ... Side spacers, 35 ... N diffusion layers, 36, 43 ... Data lines, 3
8, 45 ... Storage electrode, 39 ... Capacitor insulating film, 40
... plate electrode, 41 ... wiring, 44 ... active area,
46 ... Electrode take-out hole.

Continued front page    (72) Inventor Koji Hattori             1-280, Higashikoigakubo, Kokubunji, Tokyo             Central Research Laboratory, Hitachi, Ltd. (72) Inventor Hiroshi Shiraishi             1-280, Higashikoigakubo, Kokubunji, Tokyo             Central Research Laboratory, Hitachi, Ltd. (72) Inventor Toshihiko Tanaka             1-280, Higashikoigakubo, Kokubunji, Tokyo             Central Research Laboratory, Hitachi, Ltd. (72) Inventor Kaori Kimura             5-22-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Stock             Ceremony Company Hitachi Cho-LS System             Within F-term (reference) 2H025 AA02 AA03 AA09 AB16 AC04                       AC08 AD01 BD40 BE00 CB14                       CB41 CB43 CB45 FA12 FA17                       FA29 FA30                 2H096 AA25 BA06 EA05 FA01 GA08

Claims (5)

[Claims] 1. A step of forming a coating film of a radiation-sensitive composition on a substrate, a step of irradiating the coating film with radiation in a pattern, a step of heating the substrate after the irradiation with the radiation, and a heating of the substrate. In the pattern forming method, the method further comprises the step of exposing the coating film to an alkaline aqueous solution having a concentration of b% to remove the unirradiated portion, and the radiation-sensitive composition is represented by the general formula (1) 1] (However, R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and A represents an alicyclic hydrocarbon group together with carbon atoms C ¹ and C ^2. Represents a plurality of atoms necessary for constituting, x and y are 0, 1 or 2, respectively, and satisfy the condition of x + y = 1 or 2, and n represents a positive integer) A polymer having a structure and a compound capable of generating an acid upon irradiation with radiation, and the coating film of the polymer has a dissolution rate of 10 nm / s in an aqueous alkaline solution having a concentration of b% as described above. When the mole fraction of the structure represented by the formula (1) is a%, the polymer in the radiation sensitive composition has a mole fraction of the structure represented by the general formula (1) of (a + 5)%. that's all,
Range of (a + 20)% or less (where (a + 20)% is 1
When it exceeds 00%, it is 100% or less). 2. The pattern forming method according to claim 1, wherein the structure represented by the general formula (1) is represented by the general formula (2): (However, R ⁴ represents a hydrogen atom or a methyl group, and n represents a positive integer). 3. The pattern forming method according to claim 1, wherein the alkaline aqueous solution is a tetramethylammonium hydroxide aqueous solution. 4. The pattern forming method according to claim 1, wherein the compound that generates an acid upon irradiation with the radiation is 0.1% by weight based on 100 parts by weight of the polymer.
A pattern forming method, characterized in that the amount is in the range of 50 parts by weight to 50 parts by weight. 5. A method of manufacturing a semiconductor device having a step of forming a resist pattern on a substrate, wherein the resist pattern is formed by the pattern forming method according to any one of claims 1 to 4. And a method for manufacturing a semiconductor device.