JPH06242607A - Positive type resist composition and pattern forming method using the same - Google Patents

Abstract

PURPOSE:To provide the compsn. which has high sensitivity to radiation and is efficiently dissolved by a developer only in the exposed parts by consisting the compsn. of high-polymer compds. in which the specific quantity of functional groups for imparting alkaline solubility are replaced with the protective groups decomposed by an acid and specific compds. CONSTITUTION:This resist compsn. consists of at least one kind of the high- polymer comps. in which 5 to 50mol% of the functional groups for imparting alkaline solubility are replaced with the protective groups decomposed by the acid, at least one kind of the compds. which are at least one kind of the compds. expressed by formula I or formula II and are decomposed by the acid to be made soluble in alkali-solution and at least one kind of the compds. which generate the acid by irradiation with radiations. In the formula I, R1, R2 denote hydrogen atom, methyl group, etc.. R3 denotes a methyl group, etc.. X denotes an oxycarbonyl group, etc., Ar denotes a phenylene group, 3.5-dichlorophenylene group, etc. In the formula II, R1, R3, X and Ar are the same as in the case of the formula I and m denotes an integer from 1 to 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor resist composition for forming a highly precise ultrafine pattern and a pattern forming method using the composition.

[0002]

2. Description of the Related Art Patterning for fine processing of semiconductor elements is based on a photolithography method.

Therefore, an organic resist material sensitive to exposure to radiation is applied at the beginning of this process.

Depending on the reactivity of the resist material, the resist material is positive (the exposed portion is decomposed and becomes soluble in the developing solution and the unexposed portion remains to form a pattern) and the negative type (the unexposed portion is the developing solution). Which is soluble in water, remains exposed after development due to a cross-linking reaction in the exposed area, and shows a pattern).

For example, in the case of a positive type in which the exposed portion becomes alkali-soluble, as shown in FIG. 2, a resist 2 is coated on a semiconductor silicon substrate 1 (a) and radiation 3 is passed through a patterning mask 4. When the resist is exposed in step (b), only the part 5 corresponding to the transparent part of the mask is exposed and becomes alkali-soluble (b). Therefore, a phenomenon treatment is applied to remove the exposed part to obtain a resist pattern 6 (c).

However, these resist materials are
Since a series of reactions occur, the efficiency is poor and there are many cases where significant improvement in sensitivity cannot be expected.

Then, the chemical amplification type reaction mechanism was devised on the premise of a great improvement in sensitivity. The resist to which this is applied contains a substance that releases an acid upon irradiation with radiation.

The chemical amplification reaction is a reaction in which an acid released by irradiation of radiation causes a catalytic action by energy (for example, heat) other than exposure, and the acid decomposes or crosslinks the sensitive group. The merit of this reaction is that the acid causes a catalytic action, so that the reaction or the like occurs at an exposure amount sufficient to release the acid. Therefore, high sensitivity can be easily achieved.

For example, in the method disclosed in JP-A-59-45439, a polymer having an acid-labile group in its side chain is used, and the acid generated by light irradiation is alkali-soluble. The method of generating a functional group is used.

On the other hand, for the chemical amplification type, many multi-component systems have been devised, and the purpose thereof is also to allow each resist composition to share various reaction mechanisms.

For example, Polymer Engineering Science (Polymer Engineering S)
Science) No. 26, 1101 (1986), which comprises a novolak resin, a melamine resin, and an acid generator, and the novolak resin, which describes in JP-A-1-10640, an acetal compound, and an acid generator. Resist composition and JP-A-4-1-1
No. 58363, a resist composition comprising an acid generator in which a part of the functional groups of the alkali-soluble polymer is substituted with a protecting group, and a resist composition containing a compound having a protecting group which is decomposed by an acid in the resist composition. Have been proposed.

[0012]

However, the resist material disclosed in Japanese Patent Laid-Open No. 59-45439 described above is
Since the functional group of the side chain has hydrophobicity because it is insoluble in alkali, the adhesiveness to the substrate is poor, resist peeling occurs during development, and further, swelling of the exposed area with a developing solution occurs. , Good patterning is not expected.

In addition, the latter Polymer Engine
earning Science 26: 1101 (1
986), JP-A-1-10640 and JP-A-4-1-1.
With respect to the resist composition described in JP-A-58363, swelling can be avoided because it is a positive type, but film loss in the non-exposed portion is likely to occur, and this also inevitably suffers from problems such as reduced resolution and reduced pattern accuracy. .

Further, the longer the time after the exposure until the heat treatment, the worse the resist shape. This is because when the photoreaction generated in the resist film proceeds to the elimination reaction of the protective group by the heat treatment, water, oxygen,
This is because they come into contact with basic suspended solids and prevent their progress.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and has a high sensitivity to radiation and only the exposed portion is faithfully and efficiently dissolved in the developing solution, and further An object of the present invention is to provide a pattern forming method capable of improving the adhesiveness and preventing the deterioration of the pattern shape due to the resist material and the atmosphere in which the unexposed portion hardly dissolves in the developing solution.

[0016]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors, an alkali-soluble polymer compound in which 5 to 50 mol% of a functional group of a side chain is replaced with a protecting group which is decomposed by an acid ( a), a compound (b) in which a protective group is efficiently decomposed by an acid generated by irradiation of radiation to become alkali-soluble, and a compound (c) which generates an acid by irradiation of radiation.
It was found that the resist composition consisting of (1) and (2) is useful as a positive resist for pattern formation for semiconductors in solving the above problems.

As a process for forming a semiconductor pattern using the resist composition, by covering the resist film with a water-soluble thin film, the resist pattern can be shaped without being affected by the use atmosphere which may cause a problem. The inventors have found that they can be formed well and have completed the present invention.

That is, according to the present invention, at least one polymer compound (a) in which 5 to 50 mol% of a functional group which imparts alkali solubility is substituted with a protecting group which is decomposed by an acid, and a general formula (I):

[0019]

[Chemical 4] (In the formula, R ₁ and R ₂ are a hydrogen atom, a methyl group, a methoxy group,
A nitro group, a trifluoromethyl group, a cyano group or an aryl group, R ₃ represents a methyl group, an ethyl group, an isopropyl group, a tert-butyl group or a tert-amyl group, and X represents an oxycarboxyl group, an oxycarbonyl group, An oxymethylcarboxyl group or a sulfonate group, Ar represents a phenylene group, a 3,5-dichlorophenylene group, a naphthylene group, an antirene group or a phenanthrene group) or the general formula (II):

[0020]

[Chemical 5] (In the formula, R ₁ , R ₃ , X and Ar are as described above, and m represents an integer of 1 to _3. ) Among the compounds represented by the formula, at least one compound is decomposed by an acid. It relates to a positive resist composition comprising at least one compound (b) which becomes alkali-soluble and at least one compound (c) which generates an acid upon irradiation with radiation.

Further, according to the present invention, after forming a thin film of the positive type resist composition on a substrate, a resist coating film is formed on the resist thin film, and radiation exposure is carried out. Regarding

The present invention also comprises at least one polymeric compound (a) in which 5 to 50 mol% of the alkali-solubilizing functional groups have been replaced by a protecting group which is decomposed by an acid, and a general formula (III):

[0023]

[Chemical 6] (In the formula, R ₁ represents a hydrogen atom, a methyl group, a methoxy group, a nitro group, a trifluoromethyl group, a cyano group or an aryl group, and R ₃ represents a methyl group, an ethyl group, an isopropyl group, a tert-butyl group or a tert group. Represents an amyl group, X represents an oxycarboxyl group, an oxycarbonyl group, an oxymethylcarboxyl group or a sulfonate group, Ar represents a phenylene group, 3,5-dichlorophenylene group, 3,5-dibromophenylene group, naphthylene group, An acid is generated by irradiating with at least one compound (b) which is decomposed by an acid to become alkali-soluble and at least one compound represented by an antilene group or a phenanthrene group) It relates to a positive resist composition comprising at least one compound (c).

The present invention is also characterized in that after forming a thin film of the positive resist composition according to claim 3 on a substrate, a resist coating film is formed on the resist thin film, and radiation exposure is performed. And the pattern forming method.

[0025]

In the present invention, 5 to 50 mol% of the above-mentioned alkali-solubilizing functional group is a moiety which is not substituted with a protective group of the polymer compound (a) substituted with an acid-decomposable protective group. Since the functional group of (3) causes a strong interaction with the semiconductor substrate, the adhesiveness between the resist film and the substrate is improved.

Then, in the exposed area, the compound (c)
The generated acid becomes alkali-soluble by decomposing the protective group of the polymer compound (a). Furthermore, since the protective group of the compound (b) is also decomposed by the acid, the dissolution rate of the resist in the exposed area is accelerated.

On the other hand, in the non-exposed area, part of the highly hydrophilic functional group of the polymer compound (a) is replaced with a protective group, so that the solubility is lowered. In addition, the protective group of the compound (b) strongly interacts with the functional group of the polymer compound (a) which is not substituted with the protective group, so that the alkali solubility is further reduced.

Therefore, the compound (b) in the present invention
Is the effect of both promoting alkali solubility after decomposition and suppressing dissolution due to strong interaction of the protective groups before decomposition, which significantly improves the dissolution rate ratio of the exposed portion of the resist composition to the developer. The above problems will be eliminated.

The resist composition of the present invention is a type of composition in which an exposed portion becomes soluble in an alkali and is removed by a phenomenon, and an unexposed portion remains. Type resist composition.

The occurrence of insolubilization in the exposed portion, which is a characteristic of the chemically amplified resist, is mainly due to the contact between the use atmosphere and the resist film during the standing time from the exposure to the heat treatment. Therefore, by providing a coating thin film on the upper layer of the resist film before exposure, which is the pattern forming method of the present invention, the contact with the atmosphere in use is relaxed and the deterioration of the resist performance is prevented. It is possible to control the pattern to be used.

[0031]

EXAMPLES It is essential that the alkali-soluble polymer compound (a) used in the present invention has a structure that can withstand the dry etching step in the semiconductor process, and examples of materials satisfying such conditions include , Phenol novolac resin, cresol novolac resin,
Examples thereof include phenol-formaldehyde resins such as naphthol novolac resins, polyvinyl phenol resins, and copolymers of vinyl phenol and acrylic or styrene monomers, but are not limited thereto.

These weight average molecular weights are 4 in consideration of practical use such as film forming property and compatibility with other components and solvents.
000 to 40,000 is preferable. Molecular weight is 400
When it is 0 or less, uniform film formability cannot be obtained, resolution is lowered, and dry etching resistance is also lowered. Also, 400
In the case of 00 or more, the protecting group is decomposed by the acid generated by the irradiation of radiation, the compatibility with the compound (b) which becomes alkali-soluble becomes poor, and the dissolution rate of the exposed area also decreases, so that the residue during development is reduced. Is likely to occur.

Next, as a protective substituent for the functional group that imparts alkali solubility to the alkali-soluble polymer compound, an alkoxycarboxyl group such as tert-butoxycarboxyl group, an alkoxycarbonylmethoxy group such as tert-butoxycarbonylmethoxy group, ter
Examples thereof include an alkylcarboxyl group such as t-butylcarboxyl group and an alkoxysulfonyl group such as tert-butoxysulfonyl group.

The protection of these substituents is preferably in the range of 5 to 50 mol% of the functional group that imparts alkali solubility to the alkali-soluble polymer compound. When it is 5 mol% or less, the solubility in alkali at the time of unexposing is high and the film loss is large. Further, when the amount is 50 mol% or more, the adhesiveness to the substrate also decreases due to the decrease in the functional groups that are not substituted with a protective group, and thus development peeling of a fine pattern tends to occur.

The formula (I), (II) or (I
The compound (b) represented by II) is the following alkali-soluble compound having a phenolic hydroxyl group (hereinafter,
A phenolic compound), that is, a compound represented by the general formula (I
V):

[0036]

[Chemical 7] (In the formula, R ₁ and R ₂ are a hydrogen atom, a methyl group, a methoxy group,
Represents a nitro group, a trifluoromethyl group, a cyano group or an aryl group, Ar is a phenylene group, 3,5
A dichlorophenylene group, a 3,5-dibromophenylene group, a naphthylene group, an antilene group or a phenanthrene group is shown. ) Or a compound represented by the general formula (V):

[0037]

[Chemical 8] (In the formula, R ₁ is as described above) or a compound represented by the general formula (VI):

[0038]

[Chemical 9] (Wherein R ₁ is as described above, m is an integer of 1 to 3), all of the hydroxyl groups in the compound represented by the alkali-soluble polymer compound (a) It is substituted with the same group as the decomposing protective group.

When the protective group is an alkoxycarboxyl group, the phenolic compound (b) substituted with an acid-decomposable protective group has the formula (IV), (V) or (V).
I), dimethyl dicarbonate, diethyl dicarbonate, di (isopropyl) dicarbonate,
It can be easily synthesized by reacting with a dialkyl dicarbonate such as di (tert-butyl) dicarbonate in the presence of a basic catalyst.

When the protecting group is an alkylcarboxyl group, the formula (IV), (V) or (V
It can be easily synthesized by reacting any of I) with an alkyl acid chloride such as acetic acid chloride, propionic acid chloride, isobutyric acid chloride or valeric acid chloride.

When the protecting group is an alkoxycarbonylmethoxy group, a sodium phenolate of any one of the above general formulas (IV), (V) or (VI) and halogenated bromoacetic acid-t-butyl ester are used. It can be synthesized by a coupling reaction with an alkyl acetate.

When the protecting group is an alkoxysulfonyl group, the formula (IV), (V) or (V
It can be easily synthesized by reacting any of I) with a dialkyl sulfate such as dimethyl sulfate, diethyl sulfate, di (isopropyl) sulfate or di (tert-butyl) sulfate.

The present invention is characterized in that the resist composition contains at least one of the compounds (b) in which the functional group is substituted with a protecting group.

Examples of the compound (c) which generates an acid upon irradiation with radiation used in the present invention include triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroarsinate and triphenylsulfonium hexafluoroarsinate. Phenylsulfonium hexafluorophosphate, triphenylsulfonium trifluorosulfonate, 4
-Thiophenoxydiphenylsulfonium tetrafluoroborate, 4-thiophenoxydiphenylsulfonium hexafluoroantimonate, 4-thiophenoxydiphenylsulfonium hexafluoroarsinate,
4-thiophenoxydiphenylsulfonium hexafluorophosphate, 4-thiophenoxydiphenylsulfonium trifluorosulfonate, 4-tert-butylphenyldiphenylsulfonium tetrafluoroborate, 4-tert-butylphenyldiphenylsulfonium trifluorosulfonate, tris (4-methoxyphenyl ) Sulfonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluoroarsinate, diphenyliodonium hexafluorophosphate, diphenyliodonium trifluorosulfonate, 3,3'-dinitrodiphenyliodonium tetrafluorosulfonate 4,4'-dimethyldiphenyliodonium tetrafluoroborate, 4,4'-dimethyldiphenyliodonium hexafluoroantimonate, 4,4'-dimethyldiphenyliodonium trifluorosulfonate, 4,4'-ditert-butyldiphenyliodonium hexa Fluoroantimonate, 4,4'-ditert-butyldiphenyliodonium hexafluorophosphate, 4,4'-diter
Onium salts such as t-butyldiphenyliodonium hexafluorosulfonate, 2,4,6-tris (trichloromethyl) triazine, 2-allyl-4,6-bis (trichloromethyl) triazine, α, α, α-tribromomethyl -Phenyl sulfone, α, α, α, α ',
α ′, α′-hexachloroxylylene, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) -1,
1,1,3,3,3-hexafluoropropane, 1,
Halogen-containing compounds such as 1,1-tris (3,5-dibromo-4-hydroxyphenyl) ethane, 2-nitrobenzyl tosylate, 2,6-dinitrobenzyl tosylate, 2,4-dinitrobenzyl tosylate, methyl Examples thereof include sulfonic acid 2-nitrobenzyl ester, acetic acid 2-nitrobenzyl ester, sulfonic acid ester such as p-nitrobenzyl-9,10-dimethoxyanthracene-2-sulfonate, and the like.

In the composition of the present invention, the content of the three components is 40 to 90% by weight of the polymer compound (a) and 10 to 55% by weight of the compound (b) with respect to the total amount of the composition. %, The compound of (c) is suitably selected from the range of 0.03 to 15% by weight.

When the amount of the polymer compound (a) exceeds 90% by weight, the amount of the component (b) is decreased, so that the dissolution accelerating performance after exposure is deteriorated and the resolution is deteriorated. If the amount of the polymer compound is less than 40% by weight, the film forming property, the developability, and the dry etching performance tend to be deteriorated.

When the amount of (b) is less than 10% by weight,
The dissolution suppressing effect, which is a feature of the present invention, is reduced, and the ratio of the dissolution rate of the exposed portion to the non-exposed portion in the developing solution is reduced, so that the resolution is lowered. When (b) is more than 55% by weight, the content of the polymer compound (a) in the composition decreases, so that the film forming property tends to deteriorate and the dry etching performance also tends to deteriorate.

When the content of the compound (c) is less than 0.03% by weight, the sensitivity is lowered and pattern formation becomes difficult. On the other hand, if it exceeds 15% by weight, the compatibility in the composition is deteriorated and the pattern shape is deteriorated.

Two or more kinds of (a), (b) and (c) may be mixed.

The composition of the present invention can be prepared as a solution and applied by using a spin coater or the like for use. Any solvent can be used in that case as long as it does not react with the above-mentioned three components. For example, ethyl cellosolve acetate, methyl cellosolve acetate, diethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl ether, cyclohexanone, cyclopentanone, methyl isobutyl ketone, isoamyl acetate, dioxane, methyl butyrate, ethyl butyrate, methylmethoxypropionate, methylethoxy. Propionate, ethylethoxypropionate, 2-heptanone and the like are common.

As a material for the resist coating film used in the pattern forming method of the present invention, a polymer having a sulfonic acid or a carboxylic acid in its side chain can be used. Examples of such polymers include homopolymers of vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, methacrylic acid, acrylic acid, styrene carboxylic acid, etc., or their monomers and acrylamide, vinyl pyrrolidone, Examples thereof include copolymers with acrylic acid esters, methacrylic acid esters and the like. Further, compounds obtained by reacting a compound having a sulfonic acid with polyvinyl alcohol, polyacrylamide, polyvinyl phenol, polyvinyl aniline and the like and the like can be given.

The copolymerization ratio or introduction ratio of these is preferably such that the mole fraction of the monomer having a sulfonic acid or carboxylic acid group is 100 to 20%. If it is 20% or less, the concentration of sulfonic acid or carboxylic acid group becomes low
This is because it is difficult to obtain the desired characteristics.

Further, as the material used for the resist coating film used in the method of the present invention, not only the above-mentioned polymer main chain formed of an alkyl chain but also benzene,
A polymer formed of an aromatic ring such as pyridine, thiophene, furan, pyrrole, or imidazole can also be used. A sulfonic acid or carboxylic acid group may be bonded to these skeletons directly or through an alkyl chain or the like. In this case also, it is not necessary that all aromatic rings have sulfonic acid or carboxylic acid groups, and 30% by mole or more of the aromatic rings forming the polymer have sulfonic acid or carboxylic acid groups. If you have. This is because if it is less than this, it is difficult to obtain the desired characteristics for the same reason as above.

Further, as the material of the resist coating film used in the pattern forming method of the present invention, a mixture of a polymer compound and a compound having a sulfonic acid or a carboxylic acid can be used. In this case, as the polymer compound, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, gelatin, polyacrylamide,
Examples thereof include polyacrylic acid and polymethacrylic acid. Examples of the compound having sulfonic acid or carboxylic acid include benzenesulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, nonylbenzenesulfonic acid, nitrobenzenesulfonic acid, cyanobenzenesulfonic acid, hydroxybenzenesulfonic acid, methylsulfonic acid, trifluoric acid. Examples thereof include methanesulfonic acid, trifluoroacetic acid, nitrobenzenecarboxylic acid, cyanobenzenecarboxylic acid, hydroxybenzenecarboxylic acid and hydroxyacetic acid. The amount of sulfonic acid or carboxylic acid added is preferably 2 to 20 parts by weight with respect to 100 parts by weight of the polymer compound. If it exceeds 20 parts by weight, the concentration of sulfonic acid or carboxylic acid group becomes high, and the resolution is lowered. Also, if the amount is less than 2 parts by weight, it is difficult to obtain the desired characteristics.

In order to form the resist coating film used in the method of the present invention, the above compound is dissolved in a solvent and the solution is applied onto the resist film forming a pattern by a method such as spin coating. can give. In addition, a step of performing heat treatment after coating to remove the solvent can be appropriately added.

As the solvent used here, any solvent can be used as long as it dissolves the above-mentioned polymer compounds and does not react with them, and does not cause mixing with the underlying resist film. For example, methyl cellosolve, Ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, methoxymethyl propionate, ethoxymethyl propionate, ethoxyethyl propionate, methoxypropyl acetate, ethoxypropyl acetate, diglyme, dimethylglyme, diethylglyme, Cyclopentanone, cyclohexanone, γ
-Butyrolactone, butyl acetate, isoamyl acetate, chlorobenzene, methyl amyl ketone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ion-exchanged water and the like are common. It is preferable that the boiling point is in the range of 80 to 220 ° C. If the boiling point is lower than this, unevenness is likely to occur, and if the boiling point is higher than this, it is not easy to dry the solvent.

The resist coating material used in the pattern forming method of the present invention is one component of a polymer having a sulfonic acid or a carboxylic acid in the side chain, but in order to improve the adhesion to the resist and the coating property. A compound such as an adhesion improver or a surfactant may be added for other purposes as required.

When developing is carried out in the pattern forming method, the developer is ammonia, triethylamine,
An aqueous solution of dimethylaminoethanol, tetramethylammonium hydroxide, sodium hydroxide, sodium carbonate or the like can be used.

If desired, a compound suitable for the purpose, such as a non-metallic compound (eg, ethanol, isopropyl alcohol, etc.), can be added to the developer.

The resist composition used in the pattern forming method of the present invention is composed of three components or three or more components as described above. The improvement of the adhesiveness for improving the adhesiveness between the substrate and the material of the present invention. An agent (for example, aminosilazane, aminoalkoxysilane, alkylalkoxysilane, metal chelate, etc.) and other compounds suitable for the purpose can be added if necessary.

Before exposure in the above process, an ultra-thin film for suppressing halation or reflection of radiation at the time of exposure can be formed under the resist film.

The term "radiation" as used herein refers to ultraviolet rays, far ultraviolet rays, electron beams, X-rays, γ-rays and the like.

A pattern forming method for providing a resist coating film on the resist thin film of the present invention will be described with reference to FIG.
First, the resist 2 of the present invention is applied onto the semiconductor silicon substrate 1 (FIG. 1A), the resist coating film 7 of the present invention is applied thereon (b), and then the patterning mask 4 is applied.
When the resist is exposed to radiation through the resist, only the portion 5 corresponding to the transparent portion of the mask is exposed (c). Next, the resist coating film 7 is peeled off (d), a heat treatment is performed to accelerate the reaction of the exposed portion 5 (e), and a phenomenon treatment is performed to remove the exposed portion to obtain a resist pattern 6 ( f).

The present invention will be described below with reference to specific examples, but the invention is not limited thereto.

[Example 1] (Production of polymer compound (a) in which a portion of the alkali-soluble functional group was protected) Poly-p-vinylphenol (Mw =
6000) 1.03 mol is dissolved in 500 ml of acetone, and the system temperature is kept at 40 ° C while stirring under a nitrogen atmosphere.
The temperature was raised to. Then, 1.64 mmol of dimethylaminopyridine was added, and after 20 minutes, 0.229 mol of di (t
ert-Butyl) dicarbonate was added dropwise. After reacting for 4 hours, the mixture was poured into dilute hydrochloric acid, recovered, and then purified by reprecipitation with acetone. After that, by thoroughly washing with water and recovering the reaction product, poly-p-vinylphenol (hereinafter referred to as tBOC-PVP) (a) in which about 20 mol% of hydroxyl groups are protected with tert-butoxycarboxyl group (a). I got it. (Production of Compound (b)) 0.218 mol of bisphenol A was dissolved in 200 ml of acetone, and the system temperature was raised to 40 ° C. while stirring under a nitrogen atmosphere. Then, 1.39 mmol of dimethylaminopyridine was added, and 20 minutes later, 0.458 mol of di (tert-butyl) dicarbamate was added dropwise. After reacting for 4 hours, the reaction product was poured into pure water and thoroughly washed with water, and then the reaction product was recovered. By this reaction, tert-butoxycarboxyl-bisphenol A (hereinafter referred to as tBOC-BisA) (b) was obtained. (Preparation of resist solution) tBOC-PV obtained above
P (a) 8.4 g, tBOC-BisA (b) 3.6.
g, and 0.6 g of triphenylsulfonium trifluorosulfonate (hereinafter, trifluorosulfonate is referred to as triflate) (c) were dissolved in 26.0 g of diethylene glycol dimethyl ether, and then dissolved in 0.2 g.
Pressure filtration was performed using a 2 μm pore size filter. (Pattern forming method) The resist solution prepared and filtered as described above is applied on a silicon wafer, and then applied on a hot plate for 1 hour.
Prebaking was performed at 20 ° C. for 90 seconds to form a thin film of about 1 μm. This wafer was cooled to room temperature, and a resist coating film of about 0.05 μm was formed using an aqueous solution of polyacrylic acid containing 0.6% by weight of toluenesulfonic acid. This is exposed to light using a stepper using a KrF excimer laser as a light source, and is exposed to a hot plate at 100 ° C. for 60 hours.
Heat treatment was performed for a second. The polyacrylic acid film was removed with pure water and then developed with a 2.38% tetramethylammonium hydroxide aqueous solution for 70 seconds to examine sensitivity and resolution. At this time, the sensitivity is the exposure amount required to completely remove the resist film after development, and is 10 m in this embodiment.
It was j / cm ² .

The resolution is evaluated by the minimum line-and-space pattern that can be formed when the exposure amount is 1.2 times the sensitivity, and the resolution in this embodiment is 0.30 μmL / S. Met. Furthermore, the time from irradiation of KrF excimer laser light to heat treatment is 1
When the evaluation was carried out for 0 hours, no changes in sensitivity, pattern shape, etc. were observed.

[Examples 2 to 29] By the same method as in Example 1, except that the compounds (b) and (c) were changed to the compounds shown in Table 1, the compounds shown in Example 1 were obtained. A resist solution similar to the above was prepared. The structure of the compound (b) of Example 29 is shown in formula (VII), and is abbreviated as tBOC-m-cresol trinuclear body hereinafter.

[0068]

[Chemical 10] A pattern was formed in the same manner as in Example 1 using the resist solutions prepared in Examples 2 to 29 above. Table 1 shows the results of sensitivity and resolution of Examples 1 to 29. The sensitivity and resolution in Table 1 are the values obtained as described above.

[0069]

[Table 1]

[0070]

[Table 2]

[0071]

[Table 3] Both are 0.3 to 0.3 for KrF excimer laser exposure.
A 0.35 μm line and space pattern could be formed well.

Example 30 Production of Polymer Compound (a) in which a Part of Alkali-Soluble Functional Group is Protected Polymer compound t was prepared in the same manner as in Example 1.
BOC-PVP (a) was obtained. (Production of Compound (b)) 0.218 mol of bisphenol A was dissolved in 200 ml of anhydrous tetrahydrofuran,
The temperature of the system was raised to 40 ° C. with stirring under a nitrogen atmosphere. Then, 1.39 mmol of triethylamine was added, and 20 minutes later, 0.500 mol of trimethylacetyl chloride was added dropwise. After reacting for 4 hours, the reaction product was poured into pure water and thoroughly washed with water, and then the reaction product was recovered. By this reaction, tert-butylcarboxy-bisphenol A (hereinafter referred to as tBC-BisA) was obtained. (Preparation of resist solution) tBOC-PV obtained above
P (a) 8.4 g, tBC-BisA (b) 3.6 g,
And triphenylsulfonium triflate (c)
0.6 g was dissolved in 26.0 g of diethylene glycol dimethyl ether, and pressure filtration was performed using a 0.2 μm pore size filter. (Pattern forming method) Using the resist solution prepared above, exposure, baking and development were carried out in the same manner as in Example 1, and a 0.3 to 0.35 μm line and space pattern could be formed with good shape. .

[Examples 31 to 58] By the same method as in Example 30, except that the compounds (b) and (c) were replaced with the compounds shown in Table 2, the results are shown in Example 30. A similar resist solution was prepared. In addition, Example 58
The structure of the compound (b) is shown in formula (VIII), and is abbreviated as tBC-m-cresol trinuclear body below.

[0074]

[Chemical 11] Using the resist solutions prepared in Examples 31 to 58, patterns were formed in the same manner as in Example 30. Table 2 shows the results of the sensitivity and resolution of Examples 30 to 58. Both are 0.3-
A 0.35 μm line and space pattern could be formed well.

[0075]

[Table 4]

[0076]

[Table 5]

[0077]

[Table 6] [Example 59] (Production of polymer compound (a) in which part of alkali-soluble functional groups is protected) 2.00 mol of o-, m-cresol novolac copolymer (Mw = 8000) was added to acetone 50.
It was dissolved in 0 ml and the temperature of the system was raised to 40 ° C. while stirring under a nitrogen atmosphere. Then, 3.0 mmol of dimethylaminopyridine was added, and 20 minutes later, 0.16 mol of di (tert-butyl) dicarbonate was added dropwise.
After reacting for 4 hours, the mixture was poured into dilute hydrochloric acid, recovered, and then purified by reprecipitation with acetone. After that, thoroughly wash with water to collect the reaction product, and
% Te protected with tert-butoxycarboxy group
An rt-butoxycarboxy-o-, m-cresol novolac copolymer (hereinafter referred to as tBOC-Nov) was obtained. (Production of Compound (b)) To 0.218 mol of bisphenol A, 200 ml of 28% aqueous sodium hydroxide solution was added and stirred to dissolve. The temperature was raised to the reflux temperature of the system (around 110 ° C). Then 0.500 mol tert
-Butyl chloroacetate was added dropwise. After reacting under reflux for 4 hours, put into pure water, thoroughly wash with water,
The reaction was collected. By this reaction, tert-butoxycarbonylmethoxybisphenol A (hereinafter, tB
OMO-BisA) was obtained. (Preparation of resist solution) tBOC-No obtained above
v (a) 8.4 g, tBOMO-BisA (b) 3.6.
g, and 0.6 g of triphenylsulfonium triflate (c) were dissolved in 26.0 g of diethylene glycol dimethyl ether, and pressure filtration was performed using a 0.2 μm pore size filter. (Pattern forming method) The resist solution prepared and filtered as described above is applied on a silicon wafer, and then applied on a hot plate for 1 hour.
Prebaked at 20 ° C. for 90 seconds. The wafer was cooled to room temperature and irradiated with 248 nm Deep UV light through a mask. 1. Immediately after irradiation, heat on a hot plate at 80 ° C. for 90 seconds, return to room temperature, and then 2.
It was immersed in a 38% tetramethylammonium hydroxide aqueous solution for 60 seconds for development, and rinsed with pure water.

By this series of operations, a pattern having a rectangular shape with a line and space of 0.3 μm was obtained with good mask linearity.

[Examples 60 to 87] By the same method as in Example 59, except that the compound (b) and the compound (c) were changed to the compounds shown in Table 3, and shown in Example 59. The resist solution was prepared by the same means. The structure of the compound (b) of Example 87 is shown in formula (IX), and is abbreviated as tBOMO-m-cresol trinuclear body hereinafter.

[0080]

[Chemical 12] A pattern was formed in the same manner as in Example 59 using the resist solutions prepared in Examples 59 to 87 above. Table 3 shows the results of sensitivity and resolution of Examples 58 to 87. Both are 0.3-
A 0.35 μm line and space was formed well.

[0081]

[Table 7]

[0082]

[Table 8]

[0083]

[Table 9] [Example 88] (Production of polymer compound in which part of alkali-soluble functional groups is protected) In the same manner as in Example 59, tBOC-Nov.
I got (a). (Production of Compound (b)) 0.218 mol of bisphenol A was dissolved in 200 ml of acetone, and the system temperature was raised to 40 ° C. while stirring under a nitrogen atmosphere. Then, 1.39 mmol of triethylamine was added, and 20 minutes later, 0.500 mol of tert-butanesulfonic acid chloride was added dropwise. After reacting for 4 hours, the reaction product was poured into pure water and thoroughly washed with water, and then the reaction product was recovered. By this reaction, tert-butoxysulfonylbisphenol A (hereinafter referred to as tBOS-BisA) was obtained. (Preparation of resist solution) tBOC-No synthesized above
v (a) 8.4 g, tBOS-BisA (b) 3.6.
g, and 0.6 g of triphenylsulfonium triflate (c) were dissolved in 26.0 g of diethylene glycol dimethyl ether, and pressure filtration was performed using a 0.2 μm pore size filter. (Pattern forming method) The resist solution prepared and filtered as described above is applied on a silicon wafer, and then applied on a hot plate for 1 hour.
Prebaked at 20 ° C. for 90 seconds. The wafer was cooled to room temperature and irradiated with 248 nm Deep UV light through a mask. 1. Immediately after irradiation, heat on a hot plate at 80 ° C. for 90 seconds, return to room temperature, and then 2.
It was immersed in a 38% tetramethylammonium hydroxide aqueous solution for 60 seconds for development, and rinsed with pure water.

By this series of operations, a pattern having a rectangular cross section with a good mask linearity in a line space of 0.3 μm was obtained. [Examples 89 to 93] By the same method as in Example 88,
However, the compounds (b) and (c) were changed to the compounds shown in Table 4, and the resist solution was prepared by the same means as in Example 88. The structure of the compound (b) of Example 93 is shown in formula (X).
Abbreviated as Sm-cresol trinuclear body.

[0085]

[Chemical 13] A pattern was formed in the same manner as in Example 88 using the resist solutions prepared in Examples 89 to 93 above. Table 4 shows the results of sensitivity and resolution of Examples 89 to 93.

[0086]

[Table 10] Both are 0.3 to 0.3 for excimer laser exposure.
A 5 μm line and space could be formed well.

Comparative Example 1 (Preparation of Resist Solution) 12.0 g of tBOC-PVP synthesized in the same manner as in Example 1 and 0.6 g of triphenylsulfonium triflate were dissolved in 26.0 g of diethylene glycol dimethyl ether. After that, 0.2
Pressure filtration was performed using a μm pore size filter. (Pattern forming method) The resist solution prepared and filtered as described above is applied on a silicon wafer, and then applied on a hot plate for 1 hour.
Prebaking was performed at 20 ° C. for 90 seconds to form a thin film of about 1 μm. This wafer was cooled to room temperature, irradiated with KrF excimer laser, and heat-treated at 100 ° C. for 60 seconds on a hot plate. After that, development was performed with a 2.38% tetramethylammonium hydroxide aqueous solution for 70 seconds.
As a result, when an excimer laser of 30 mJ / cm ² was irradiated and then immediately heated to form a pattern, a 0.3 μm line-and-space pattern could be developed, but heating was performed after 30 minutes or more after exposure. In some cases, it became impossible to resolve a pattern of 0.5 μm or less. Further, when the time until heating after exposure was changed, the sensitivity decreased with the passage of time.

[0088]

As described above, when the resist composition of the present invention is used as a semiconductor resist, the solubility of the unexposed area in a developing solution can be improved by containing at least one compound (b) in the composition. Further, the degradability of the protective group by the compound (c) which generates an acid upon irradiation with light is improved in the exposed portion, and therefore the solubility in the developing solution is promoted. In particular, when the compound (b) has a tert-butoxycarboxyl group or a tert-butoxycarbonylmethoxy group in the structure, the ratio of the dissolution rate of the exposed portion of the resist thin film to the unexposed portion in the developing solution is It becomes 4 digits or more, and the cross-sectional shape of the pattern becomes closer to a rectangle.

In the pattern forming method of the present invention, a resist coating film is formed on the above resist film and then exposed to light so as to prevent chemical amplification reaction due to water, oxygen, basic floating substances and the like contained in a use atmosphere. Inhibition can be prevented, and deformation of the pattern due to the time from exposure to baking can be suppressed. By making the cross-sectional shape of the pattern rectangular, the dry etching performance after patterning is also improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a pattern forming method according to the present invention.

FIG. 2 is a diagram showing a conventional pattern forming method.

[Explanation of symbols]

 1 semiconductor substrate 2 resist thin film 3 radiation 4 patterning mask 5 exposed portion 6 resist pattern 7 resist coating film

[Procedure amendment]

[Submission date] June 23, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

The generation of the insolubilized layer on the surface of the exposed portion, which is a characteristic of the chemically amplified resist, is mainly due to the contact between the use atmosphere and the resist film during the standing time from the exposure to the heat treatment. Therefore, by providing a coating thin film on the upper layer of the resist film before exposure, which is the pattern forming method of the present invention, the contact with the atmosphere in use is relaxed and the deterioration of the resist performance is prevented. a pattern that it is possible to control absence Rukoto.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

These weight average molecular weights are 4 in consideration of practical use such as film forming property and compatibility with other components and solvents.
000 to 100,000 is preferable. Molecular weight is 40
In the case of 00 or less, uniform film formability cannot be obtained, the resolution is lowered, and the dry etching resistance is also lowered. Also, 10
In the case of 0000 or more, the protecting group is decomposed by the acid generated by the irradiation of radiation, the compatibility with the compound (b) which becomes alkali-soluble is deteriorated, and the dissolution rate of the exposed area is also reduced. Is likely to occur.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location G03F 7/029 7/30 7124-2H H01L 21/027 (72) Inventor Shigeru Kubota Tsukaguchi Honcho, Amagasaki 8-1-1, Mitsubishi Electric Corporation, Material and Device Research Center (72) Inventor, Hiroshi Kozuka 8-1-1, Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric, Ltd., Material and Device Research Center

Claims (4)

[Claims] 1. 5 to 5 functional groups that impart alkali solubility
0 mol% is at least one polymer compound (a) substituted with an acid-decomposable protecting group, and a compound represented by the general formula (I): (In the formula, R ₁ and R ₂ are a hydrogen atom, a methyl group, a methoxy group,
A nitro group, a trifluoromethyl group, a cyano group or an aryl group, R ₃ represents a methyl group, an ethyl group, an isopropyl group, a tert-butyl group or a tert-amyl group, and X represents an oxycarboxyl group, an oxycarbonyl group, Indicates either an oxymethylcarboxyl group or a sulfonate group, Ar is a phenylene group, 3,5-dichlorophenylene group, 3,5-dibromophenylene group,
A naphthylene group, an antilen group, or a phenanthrene group) or the general formula (II): (In the formula, R ₁ , R ₃ , X and Ar are as described above, and m is an integer of 1 to 3), and at least one of the compounds represented by A positive resist composition comprising at least one compound (b) that becomes a compound and at least one compound (c) that generates an acid upon irradiation with radiation. 2. A pattern forming method comprising forming a thin film of the positive resist composition on a substrate, forming a resist coating film on the resist thin film, and performing radiation exposure. 3. 5 to 5 functional groups that give alkali solubility
At least one polymer compound (a) in which 0 mol% is substituted with a protecting group which is decomposed by an acid;
I): (In the formula, R ₁ represents a hydrogen atom, a methyl group, a methoxy group, a nitro group, a trifluoromethyl group, a cyano group or an aryl group, and R ₃ represents a methyl group, an ethyl group, an isopropyl group, a tert-butyl group or a tert group. Represents an amyl group, X represents an oxycarboxyl group, an oxycarbonyl group, an oxymethylcarboxyl group or a sulfonate group, Ar represents a phenylene group, 3,5-dichlorophenylene group, 3,5-dibromophenylene group, naphthylene group, An acid is generated by irradiating with at least one compound (b) which is decomposed by an acid to become alkali-soluble and at least one compound represented by an antilene group or a phenanthrene group) A positive resist composition comprising at least one compound (c). 4. A pattern characterized by forming a thin film of the positive resist composition according to claim 3 on a substrate, forming a resist coating film on the resist thin film, and performing radiation exposure. Forming method.