JPH0215270A - Photoresist composition - Google Patents

Abstract

PURPOSE:To obtain high transparency in the deep ultraviolet regions and the like by using a composition of a polymer having hydroxystyrenes, a specified cross-linking agent,and a compound capable of generating acid upon irradiation with actinic rays. CONSTITUTION:The photoresist composition is obtained by adding the compound to be allowed to produce acid by irradiation with the actinic rays to a combination of the polymer having the repeating units each represented by formula I and at least one of the cross-linking agents represented by formulae II, III, and IV. In the formulae I-IV, each of R1-R3 is H or 1-5C alkyl; each of R4-R7 is H, OH, 1-5C alkyl, or such alkoxyl; X is O or methylene or the like; R11 is H or 1-5C alkyl; and each of R12-R15 same as R4.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a photoresist composition suitable for forming a fine resist pattern, and more specifically, a photoresist composition suitable for forming a fine resist pattern. The present invention relates to a photoresist composition that has high sensitivity, high resolution, and excellent heat resistance. The photoresist composition of the present invention can be used in the field of electronic industry, such as being used for manufacturing high-density integrated circuits such as LSI and VLSI, and also for manufacturing photomasks used in their manufacturing. Widely used in

[Prior Art] In recent years, semiconductors have become increasingly highly integrated, and the demands for miniaturization are becoming more and more severe.

Therefore, in terms of manufacturing, it is becoming difficult to cope with conventional processes, and the introduction of new technologies is being considered. Efforts are being made to establish ultra-fine pattern processing technology by using deep ultraviolet rays with shorter wavelengths and excimer lasers instead of conventional ultraviolet rays as light sources used in lithography. Especially K
Development of a reduction projection exposure method using an rF excimer laser is underway.

Resist compositions used as such resists for short wavelength lithography include compositions whose main component is a resin that can be depolymerized by irradiation with actinic rays, such as polymethyl methacrylate or polymethyl glutarimide; A composition has been proposed in which an alkali-soluble resin such as a cresyl-formaldehyde novolac resin is mixed with an 0-naphthoquinonediazide sulfonic acid ester derivative as a photosensitizer.

However, although the main chain cleavage type resist has excellent resolution, it has a wavelength of 2
There were problems such as poor sensitivity at 48 nm and poor RIE resistance. In addition, although the novolak resin resist has excellent sensitivity and HE resistance, K+F
At 248 nm, the wavelength of excimer laser, O-
Because the light absorption of the naphthoquinonediazide sulfonic acid ester derivative does not decrease after exposure, the light does not reach the bottom of the resist during exposure, resulting in a strong trapezoidal pattern profile and large film thinning. There was a problem.

These problems are due to the fact that the main chain cut type resist does not contain an aromatic ring in the resin, and the novolak resin resist has poor transparency of the resist film.

[Problems to be Solved by the Invention] As described above, conventional photoresist compositions have poor sensitivity and RIE resistance when used in excimer laser lithography.
There is no one that satisfies all the requirements in terms of properties, pattern shape, etc., and it is still difficult to say that it is practical.

Therefore, the present invention has been made to solve the above-mentioned problems. That is, an object of the present invention is to provide a photoresist composition that has excellent transparency in the deep ultraviolet and excimer laser wavelength regions, has high sensitivity and high RIE resistance, and is capable of obtaining fine patterns with good pattern profiles. It is in.

[Means for Solving the Problems] In view of the above circumstances, the present inventors have made extensive studies and have developed a cross-linked polymer containing hydroxystyrene with high transparency in the deep ultraviolet and excimer laser wavelength ranges. By using a composition in which a compound that can generate an acid when irradiated with the above-mentioned light (hereinafter referred to as a photoacid generator) is used, the transparency of the resist in this wavelength range can be improved, and the exposed areas of the resist can be improved. The present inventors have discovered that it is possible to fully expose the bottom part of the film, and a fine pattern with a good pattern profile can be obtained, and that the above object can be achieved as a result, and the present invention has been completed.

That is, the photoresist composition of the present invention comprises a polymer containing the following general formula (I) (wherein R1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms) and the following general formula (n), ( m), (]V) R20CH2CH20R2 (In the formula, R2 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.) ○ (In the formula, R3 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R4 to R7 are each a group selected from a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, or an alkoxyl group having 1 to 5 carbon atoms, and may be the same or different.

X is an oxygen atom, a methylene group, -N-R8 or -C-R9
R. represents. Here, R8 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R9, R, and o are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a hydroxyl group, and are the same. It may be different or different. ) R+3RL4 (In the formula, R11 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R□2, R13, R14, and R15 each represent a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, or a carbon They are groups selected from alkoxyl groups of numbers 1 to 5, and may be the same or different.

) A photoresist composition is provided, in which a compound capable of generating an acid upon irradiation with actinic rays is added to a crosslinking agent represented by any of the above.

The photoresist composition of the present invention will be explained in detail below.

The polymer used in the photoresist composition of the present invention is a polymer or copolymer having a structural unit represented by the above formula (I), and is a polymer or copolymer having a structural unit represented by the above formula (I), and is a polymer or a copolymer having a structural unit represented by the above formula (I), and is a polymer or a copolymer that is polymerized by radical polymerization, ionic polymerization, etc. of hydroxystyrene or α-methylhydroxystyrene, etc. It can be obtained by radical copolymerization or ionic copolymerization of hydroxystyrene, α-methylhydroxystyrene, or other vinyl monomers. In each polymer or copolymer, the -OH group may be located at any of the 0, 2m, and p positions with respect to the polyvinyl skeleton. Other vinyl monomers used in the copolymer may be used as long as they can be copolymerized with hydroxystyrene or the like.

Specifically, styrene monomers such as styrene, chlorostyrene, chloromethylstyrene, vinyltoluene, and α-methylstyrene; acrylic acid monomers such as acrylic acid, methyl acrylate, methacrylic acid, methyl methacrylate, and phenyl methacrylate; Further, vinyl acetate monomers such as vinyl acetate and vinyl benzoate can be mentioned. These polymers or copolymers have excellent resin transparency compared to cresol-formaldephod novolac resins, which are similar alkali-soluble resins, and can be suitably used in the present invention.

In the polymer used in the photoresist composition of the present invention, it is desirable that the proportion of the structural unit represented by the formula (1) is 50% or more of the total structural units. If it is less than 50%, the solubility in a basic developer is adversely affected and development becomes difficult.

In addition, the polymer used in the present invention has a weight average molecular weight (Mw)
is 1000-100,000, preferably 2000-5
0000 is used. Outside the above range, sensitivity, resolution, coating properties, heat resistance, etc. will be adversely affected.

Next, the crosslinking agent used in the photoresist composition of the present invention is a compound obtained by converting a 5-membered ring, a 6-membered ring, or a bicyclo compound that does not contain a carbon-carbon double bond or a carbon-nitrogen double bond in its skeleton into an alkoxymethylol compound. These crosslinking agents have excellent transparency at deep ultraviolet rays and excimer laser wavelengths compared to crosslinking agents having skeletons such as melamine, benzoguanamine, or acetoguanamine, and can be suitably used in the present invention. Specific examples include, but are not limited to, the following. Further, these crosslinking agents can be used alone or in combination of two or more.

The compounds used as photoacid generators in the photoresist compositions of the present invention generate acids upon irradiation with actinic light, particularly deep ultraviolet rays and excimer laser, and many compounds are generally widely known.

Examples of such compounds include halogenated diphenylethane derivatives represented by the following general formula (V), sulfonic acid ester derivatives represented by the following general formula (VI), and iodonium salts represented by the following general formula (■). , or a sulfonium salt represented by the following general formula (■).

1C The halogenated diphenylethane derivative represented by the above general formula (V) produces a halogen acid upon irradiation with actinic rays, and R86 and R1□ in the formula are a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, A hydroxyl group or a nitro group, R18 is a hydrogen atom, a hydroxyl group, or R29CONH-CR2, is an alkyl group. ), RI9 is a halogen atom, and R2o1R21 are each a hydrogen atom, a halogen atom, or an alkyl group.

The sulfonic acid ester derivative represented by the above general formula (VI) produces a sulfonic acid upon irradiation with actinic rays, and R22 in the formula is 18o3 of the sulfonic acid to be produced.
This is a group that blocks the H site.

Such groups include (R3o is an alkylene group, alkenylene group, or arylene group, R3□, R3□, R33, R35, and R
3, each alkyl group or aryl group, R34
, 'R3e is an aryl group, and R37 and R38 are each a hydrogen atom, an alkyl group, or an aryl group.

) can be mentioned. Moreover, R23 is an alkyl group,
Or it is an aryl group.

The iodonium salt represented by the above general formula (■) and the sulfonium salt represented by the above general formula (■) produce a Lewis acid upon irradiation with actinic rays, and R24, R25, R26 in the formula , or an aryl group, X is B
F6 PF6- AsF65bF6- ClO4
− is.

Specific examples of such photoacid generators include (IV-
1) (■ (■ G convex-NH-0-5O2GCH3) (■ (■ (■ (■ (■ (■-2) (■-1) (■-2) etc., but are limited to These photoacid generators can be used alone or in combination of two or more.

In the present invention, the content ratio of each component is 10
It is desirable to contain 3 to 30 parts by weight of the crosslinking agent and 0.1 to 10 parts by weight of the photoacid generator relative to 0 parts by weight.

If it deviates from the above range, it will have an adverse effect on the shape of the baton and the resolution.

The photoresist composition according to the present invention is soluble in organic solvents, and when used in the fabrication of integrated circuits, it is usually used in solutions (
It is used in the form of a resist solution). In this case, the composition is generally 1 to 50% by weight in an organic solvent, preferably 5 to 3% by weight.
It is dissolved and adjusted at a ratio of 0% by weight. In this case, the solvent used is one that uniformly dissolves each component of the photoresist composition of the present invention, and after applying it to the surface of a substrate such as silicon or aluminum, evaporates the organic solvent to form a uniform and smooth coating. Preferably, a film can be obtained. Specifically, ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone, cellosolve solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, and ether solvents such as tetrahydrofuran and diethylene glycol dimethyl ether. , ethylene glycol monoethyl ester, ethylene glycol monomethyl acetate, and other ester solvents, but are not limited thereto.

The above organic solvents may be used alone or in combination of two or more.

In addition to the above-mentioned components, the negative photoresist composition of the present invention may optionally contain sensitizing columns, dyes, plasticizers, other resins, various inhibitors such as thermal reaction inhibitors, adhesion improvers, etc. You can. The photoresist composition of the present invention can be used to form a relief pattern using conventional photoresist techniques by adjusting the resist solution as described above.

The method for forming this relief pattern will be explained below.

(1) The resist solution prepared as described above is applied to a substrate to form a resist film with a thickness of 1 to 1.5 μm. This coating on the substrate can be performed using, for example, a spinner.

(2) The temperature of the substrate is 60-120°C, preferably 80-120°C.
Dry at 90°C for 20 to 60 minutes. (Pre-bake) (3) This coating film is irradiated with deep ultraviolet rays and excimer laser through a photomask chart.

(4) Heat the exposed substrate to 80 to 90°C for 20 minutes to 6
Heat for 0 minutes. (Intermediate bake) (5) A relief pattern is obtained by washing out the unexposed areas with a developer. As a developer, sodium hydroxide,
For example, a weak alkaline aqueous solution of potassium hydroxide, sodium metasilicate, tetramethylammonium hydroxide, etc. with a concentration of 5% by weight or less can be used. (6) The developed substrate is heated to a temperature of 80 to 130°C, preferably 9
Dry at 0-120°C for 20-60 minutes. (Bost baking) The relief pattern thus formed has a resolution of 1 μm or less and has good heat resistance.

Furthermore, a substrate can be etched using the negative photoresist composition of the present invention and the pattern formed as described above as a mask.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

(Example 1) Poly(p-hydroxystyrene) (weight average molecular weight = 5
000) I Og, 2.0 g of tetrabutoxymethylol acetylene urea and 0.48 g of 1.1 bis(p-chlorophenyl)-2,2,2-) IJ'
A photoresist composition consisting of
The resist solution was prepared by filtration with a filter of 1.0 m.

This resist solution was mixed with hexamethylene disilazane (HMD).
S) was spin-coded at 2000+pm/60 seconds onto a silicon wafer using a spin coater and coated at 3000 r.
Coated at pm 15Q seconds. This wafer was prebaked in an oven at 80° C. for 30 minutes to obtain a coating film of 1.0 μm. Next, the above coating film was passed through a patterned chrome mask and applied to a contact aligner-PLA-521F.
Deep ultraviolet exposure was performed using a CM-250 mirror (manufactured by Canon). After exposure, the exposed area was crosslinked by heating the wafer on a hot plate at 100° C. for 1 minute. After cooling the wafer, it was rapidly developed by immersion in a 1.7% aqueous solution of tetramethylammonium hydroxide for 1 minute.
The unexposed areas were dissolved to obtain a pattern. Furthermore, 10
After post-baking at 0°C for 30 minutes, the characteristic curve of irradiation dose and residual film rate was determined by measuring the film thickness.
mi/cnf (254nm) sensitivity (remaining film rate 5
0% irradiation dose) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.7 μm was resolved.

(Example 2) 1,1-bis(p-chlorophenyl) in Example 1
-2,2,2-) Lichloroethane was replaced by α-tosyloxydeoxybenzoin, but the result was 30 mi/car (254n
m) sensitivity (irradiation amount at a residual film rate of 50%) was obtained. Also,
As a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.7 μm was resolved.

(Example 3) 1,1-bis(p-chlorophenyl) in Example 1
The same procedure was performed except that diphenyliodonium tetrafluoroborate was used instead of -2,2,2-trichloroethane, and the result was 28 mj/c[l? (2
54 nm) (irradiation amount at a residual film rate of 50%) was obtained.

Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.7 μm was resolved.

(Example 4) 1,1-bis(p-chlorophenyl) in Example 1
-2,2,2-) The same procedure was performed except that triphenylsulfonium hexafluorophosphate was used instead of dichloroethane, and the result was 25 m1/crl.
Sensitivity of (254++m) (irradiation dose at 50% residual film rate)
I got it. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.7 μm was resolved.

(Example 5) Instead of poly(p-hydroxystyrene) in Example 1, p-hydroxystyrene-styrene copolymer (
Weight average molecular weight -5000, styrene content -30%), 1,3-dimethoxymethylolpropylene urea was used instead of tetrabutoxymethylol acetylene urea, but the result was 21 mj/c ( 254 nm) (irradiation amount at a residual film rate of 50%) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.7 μm was resolved.

(Example 6) Instead of poly(p-hydroxystyrene) in Example 1, p-hydroxystyrene-styrene copolymer (
Weight average molecular weight = 5 [IQθ, styrene content = 30%
) and using 1,3-dimethoxymethylolethyleneurea instead of tetrabutoxymethylolacetyleneurea, the result was 23 mj/
cnf (254 nm) sensitivity (irradiation dose at a residual film rate of 50%) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 07 μm was resolved.

(Comparative Example 1) The same procedure was performed as in Example 1 except that Cymel 303, a partially methylated product of hexamethylol melamine, manufactured by Mitsui Suyanamitsu Co., Ltd. was used instead of tetrabutoxymethylol acetylene urea. As a result, 18 mj/
A sensitivity (irradiation dose at a residual film rate of 50%) of cl (254 nm) was obtained. Moreover, as a result of observing the formed pattern with an electron microscope, it was not possible to resolve a fine pattern of 0.7 μm.

[Effects of the Invention] As explained above, the photoresist composition of the present invention has high transparency in the deep ultraviolet and excimer laser wavelength regions. As a result, sensitivity, resolution, and contrast can be significantly improved in lithography using the above-mentioned light beam as a light source, which is necessary for improving the resolution of resists.Furthermore, since the alkali developability is good, pattern swelling can be prevented. , it is possible to form a fine photoresist pattern with high precision without the risk of producing undeveloped images. Therefore, these compositions can be used not only as resists for manufacturing high-density integrated circuits such as LSI and VLSI, where requirements for resolution will become increasingly strict in the future, but also for manufacturing photomasks used in their manufacturing. It can be used widely in the field of electronic industry.

Claims (1)

[Claims] 1. A polymer containing the following general formula (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) (In the formula, R_1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms ) and at least one crosslinking agent represented by the following general formulas (II), (III), and (IV), and a compound capable of generating an acid upon irradiation with actinic rays is added to the system. photoresist composition. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R_2 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) (In the formula , R_3 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R_4 to R_7 are each selected from a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, or an alkoxyl group having 1 to 5 carbon atoms. are groups and may be the same or different at the same time. X is an oxygen atom, a methylene group, =N-R_8 or =C-R
Represents _9R_1_0. Here, R_8 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R_9 and R_1_0 are each a group selected from a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a hydroxyl group, and are the same. may also be different. ) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(IV) (In the formula, R_1_1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R_1_2, R_1_3, R_1_4
, R_1_5 are each a group selected from a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 5 carbon atoms, or an alkoxyl group having 1 to 5 carbon atoms, and may be the same or different. )