JPH06118647A - Negative type photosensitive composition - Google Patents

Abstract

PURPOSE:To prevent the generation of swelling and to enable a pattern profile high in resolution to be formed by using a novolak resin made from a specified phenol and a specified aldehyde for an alkali-soluble resin. CONSTITUTION:The alkali-soluble resin comprises the novolak resin made from phenols comprising >=75mol% m-cresol, for example, m-cresol alone, or together with other preferable phenols, such as phenol, o- or p-cresol, xylenol, and aldehyde, preferably, such as formaldehyde, and this resin can be obtained by polycondensing the phenol and the aldehyde under acid conditions, and a mixture of >=2 kinds of each of phenols and aldehydes can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a negative photosensitive composition sensitive to radiation, and more particularly to a negative photoresist used for producing a semiconductor integrated circuit.

[0002]

2. Description of the Related Art High integration of semiconductor integrated circuits has been promoted at a rate of four times in three years, as is generally called, for example, in a dynamic random access memory (DRA).
Taking M) as an example, a product having a storage capacity of 4 M bits is currently in full-scale production. The demand for photolithography technology, which is indispensable for the production of integrated circuits, is increasing year by year. For example, in the production of 4Mbit DRAM,
0.8 μm level lithography technology is required,
In 16Mbit and 64Mbit DRAMs, which have been further integrated, 0.5 μm and 0.3 μm, respectively.
Levels of lithography are expected to be needed. Therefore, development of a resist that can be applied to half-micron lithography has been earnestly desired.

In recent years, there has been a method of using a phase shift mask proposed by Levenson et al. As a means for improving the resolution. When this method is used, a resolution of about 50% is obtained as compared with a conventional mask. Can be expected to improve.
However, this method requires the use of a negative resist depending on the pattern arrangement. Therefore, development of high-performance negative resist is awaited.

On the other hand, as a negative resist used for photolithography, a resist using a cyclized rubber and bisazide as a crosslinking agent is well known. However, since this system requires an organic solvent for development, swelling occurs during development, and the image resolution is limited to about 3 μm. Therefore, it is not suitable for manufacturing a highly integrated device. Further, the organic solvent used for development has many problems in terms of environment, health and flammability.

Further, a positive resist composed of naphthoquinonediazide and an alkali-soluble novolac resin is also known. However, since this system is a positive type, it is difficult to apply the phase shift method, which is effective in half-micron lithography. This resist is 300
There is a large absorption below nm, and there is a drawback that the pattern profile is significantly deteriorated when short wavelength exposure is performed.

On the other hand, candidates for high resolution lithography include X-ray lithography and electron beam lithography. The former is conspicuously behind in terms of hardware and resist, and the latter is mass-produced in terms of throughput. I can not cope.

In recent years, a chemically amplified negative resist containing an acid-curable resin system and an ultraviolet acid generator has been proposed (for example, JP-A-62-164045). This resist composition is highly sensitive because it utilizes chemical amplification,
The resolution is not sufficient, and it is necessary to further increase the resolution in order to adapt to mass production of 16 Mbit and 64 Mbit semiconductors. Therefore, at the present time, it is possible to develop a negative photosensitive composition that does not swell during development, has high resolution, has photosensitivity to ultraviolet light, and is compatible with the phase shift method. It is strongly desired to deal with.

[0008]

As described above, a resist which does not swell during development and can be applied to the phase shift method is an essential resist for half-micron lithography. None of the naphthoquinone diazide-novolak-based resists satisfy these two conditions.

An object of the present invention is to solve the above-mentioned problems of the prior art and to develop a resist having good pattern profile and high sensitivity, which is sensitive to ultraviolet light.

[0010]

Means for Solving the Problems The present inventors have conducted various studies to achieve the above object, and as a result, in a resist composition in which an alkali-soluble resin, a crosslinking agent, and an acid generator are combined, It has been found that when a specific novolac resin is used as the resin, a high-performance negative photoresist composition capable of forming a high-resolution pattern profile without swelling is obtained.

The present invention has been completed based on such findings, and the gist thereof is a negative-type photosensitive material containing an alkali-soluble resin, a cross-linking agent that acts on the alkali-soluble resin under acidic conditions, and an acid generator. Negative composition, wherein the alkali-soluble resin is a novolac resin synthesized from phenols and aldehydes, 75 mol% or more of which is m-cresol.
Exist in.

The present invention will be described in detail below. The alkali-soluble resin used in the present invention contains 75 mol% or more m
-A novolak resin synthesized from cresol phenols and aldehydes. This resin is m-
It can be obtained by polycondensing a mixture of phenols containing 75 mol% or more of cresol or m-cresol with aldehydes under acidic conditions. m-
Suitable phenols other than cresol include phenol, o-, or p-cresol,
Xylenol, resorcinol, pyrogallol, bisphenol, bisphenol A, trisphenol, o
-, M-, or p-ethylphenol, n-, or i-propylphenol, n-, s-, or t-butylphenol, 1-, or 2-naphthol may, for example, be mentioned. The most preferred aldehyde is formaldehyde, but acetaldehyde, propionaldehyde, benzaldehyde, furfural and the like can also be preferably used. These phenols and aldehydes can be used alone or in admixture of two or more. It is preferable that these novolac resins have a high glass transition temperature, and specifically those having a glass transition temperature of 75 ° C. or higher.

In order to obtain a better pattern profile, in the present invention, it is preferable to use a novolac resin having a dissolution rate in a developing solution in a specific range among the novolac resins. Specifically, the dissolution rate in the film thickness direction of the film of the novolac resin in a 2.38 wt% aqueous solution of tetramethylammonium hydroxide as a developer at 25 ° C. (hereinafter, simply referred to as dissolution rate) is
250 to 20,000 Å / s is preferable, and further 500
It is more preferably up to 10,000Å / s. Use of a novolak resin having a too high dissolution rate is not preferable because the sensitivity of the formed resist composition is significantly lowered. The dissolution rate of the novolac resin can be controlled by appropriately selecting the type and amount of phenols and aldehydes, reaction conditions and the like.

The second component of the composition of the present invention, which is a cross-linking agent that acts on the alkali-soluble resin under acidic conditions, is:
The compound is not particularly limited as long as it is a compound that undergoes a crosslinking reaction with the alkali-soluble resin used, but examples include melamine, benzoguanamine, glycoluril or a compound obtained by allowing formalin to act on urea or an alkyl-modified compound thereof, an epoxy compound, a resole compound and the like. To be

Specifically, Cymel (registered trademark) 300, 301, 303, 350, 73 manufactured by Mitsui Cyanamide Co., Ltd.
6,738,370,771,325,327,70
3,701,266,267,285,232,23
5,238,1141,272,254,202,11
56,1158 can be mentioned as an example of a compound in which formalin is allowed to act on melamine or an alkyl modified product thereof. In addition, Cymel (registered trademark) 1123, 11
25,1128 can be mentioned as an example of a compound obtained by allowing formalin to act on benzoguanamine or an alkyl-modified product thereof. Cymel (registered trademark) 1170,1
171, 1174, 1172 can be mentioned as an example of a compound obtained by allowing formalin to act on glycoluril or an alkyl-modified product thereof. As an example of a compound obtained by reacting urea with formalin or an alkyl-modified compound thereof, UFR (registered trademark) 65,3 manufactured by Mitsui Cyanamide Co., Ltd.
00 can be mentioned.

As an example of the epoxy compound, a novolac epoxy resin (YDP N-638,7 manufactured by Tohto Kasei Co., Ltd.) is used.
01,702,703,704, etc.), amine epoxy resin (manufactured by Tohto Kasei Co., YH-434, etc.), bisphenol A epoxy resin, sorbitol (poly) glycidyl ether, (poly) glycerol (poly) glycidyl ether, pentaerythritol ( Poly) glycidyl ether, triglycidyl trishydroxyethyl isocyanurate, allyl glycidyl ether, ethylhexyl glycidyl ether, phenyl glycidyl ether, phenol glycidyl ether, lauryl alcohol glycidyl ether, adipic acid glycidyl ether, phthalic acid glycidyl ether, dibromophenyl glycidyl ether, dibromo Neopentyl glycol diglycidyl ether, glycidyl phthalimide, (poly) ethylene glycol glycidyl Ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether,
Butyl glycidyl ether and the like can be mentioned.

Of these, particularly preferred compounds include compounds having a —N (CH ₂ OR) ₂ group (wherein R represents an alkyl group or a hydrogen atom) in the molecule. Specifically, a compound obtained by reacting urea or melamine with formalin or an alkyl-modified compound thereof is particularly preferable.
The third component of the composition of the present invention is an acid generator. The acid generator used in the present invention is not particularly limited as long as it is a compound capable of generating an acid with light in the range of about 150 to 400 nm, and for example, Polymeric Materials Science and Engineering Vol. 61, p. 63 (American Chemical Society). To J. V. Onium salts and sulfonates as disclosed by Klibero, or Japanese Examined Patent Publication No.
Examples thereof include a photosensitive organic halogen compound as disclosed in 3574. Specifically, 3,4-dibromosulfolane, 3,4-dichlorosulfolane, carbon tetrabromide, 1,2,3,4-tetrabromobutane, 1,1,
2,2-tetrabromoethane, hexabromocyclohexane, hexabromocyclododecane, tribromomethylphenyl sulfone, tris (2,3-dibromopropyl) isocyanurate, methylene glycol bis (2,2
3-dibromopropyl) ether, tris (tribromomethyl) -s-triazine, tris (dibromomethyl)
-S-triazine, tris (trichloromethyl) -s-
Triazine, tris (dichloromethyl) -s-triazine, diphenyliodonium salt, pentaerythritol tetrabromide, 2,3-dibromopropene, 1,2,
3-tribromopropane, 3,4,5-tribromosalicylanilide, 1,1,3,3-tetrabromoacetone, 2,3-dibromopropanol, dibromotetrachloroethane, 1,6-dibromohexane, 1, 4-dibromobutane, iodoform, hexachloroacetone and the like can be mentioned.

The mixing ratio of the alkali-soluble resin, the crosslinking agent and the acid generator in the resist composition of the present invention is usually
Cross-linking agent 5 to 70 per 100 parts by weight of alkali-soluble resin
Parts by weight and 0.1 to 30 parts by weight of the acid generator. In the resist composition of the present invention, it is effective to add a sensitizer in order to increase the sensitivity or expand the photosensitive wavelength region. Examples of preferred sensitizers include N-phenyl-1-naphthylamine,
Examples thereof include N, N-diphenyl-1-naphthylamine, N-phenyl-N-benzyl-1-naphthylamine, N-phenyl-N-styryl-1-naphthylamine, phenothiazine derivatives and phenoxazine derivatives. When the sensitizer is added, the addition amount is usually 0.1 to 30 parts by weight based on 100 parts by weight of the alkali-soluble resin.

The composition of the present invention is usually used by dissolving it in a solvent, but the solvent is not particularly limited as long as it has a sufficient solubility for the resin and the photosensitizer and gives a good coating property. None, for example, cellosolve solvent such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl acetate, ethyl acetate, methyl acetate, amyl acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl methoxypropionate. , Ester solvents such as methyl ethoxypropionate and ethyl ethoxypropionate, highly polar solvents such as diglyme, dimethylformamide and N-methylpyrrolidone, or mixed solvents thereof, or mixed solvents obtained by adding aromatic hydrocarbons to these. Etc. The solvent is usually used in a weight ratio of 1 to 2 with respect to the total amount of solids.
The range is 0 times.

The composition of the present invention may further contain various additives such as dyes, pigments, coatability improvers, development improvers and adhesion improvers. The negative photosensitive composition of the present invention comprises the following coating, exposure, and post-exposure bake (post exposure bake: hereinafter PEB).
Abbreviated), and is used as a photoresist through each step of development.

A spin coater is usually used for coating,
A suitable film thickness is about 0.5 μm to 2 μm. For exposure, a mercury lamp 436 nm, 365 nm, 254n
m, excimer laser 157 nm, 193 nm, 2
Light of 22 nm and 248 nm is preferably used. Light at the time of exposure may be broad instead of monochromatic light. Especially 3
00 nm to 380 nm is preferable, and i-line (3
65 nm) is preferred.

PEB usually uses a hot plate, and
It is carried out at a temperature of about 0 to 140 ° C. for about 15 seconds to 10 minutes. A convection oven may be used instead of the hot plate. This generally requires a longer time than using a hot plate.

For developing the composition of the present invention, potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, inorganic alkalis such as aqueous ammonia, ethylamine, n-propylamine, etc. Primary amines, diethylamine, di-n
An alkali comprising an aqueous solution of an alkaline compound such as a secondary amine such as propylamine, a tertiary amine such as triethylamine or trimethylamine, a quaternary ammonium salt such as tetramethylammonium hydroxide or trimethylhydroxyethylammonium hydroxide A developer is preferably used. If necessary, an alcohol, a surfactant or the like may be added to the developer for use.

The photoresist solution and the developing solution are
Each is used after being filtered with a microfilter to remove dust during use. INDUSTRIAL APPLICABILITY The negative photosensitive composition of the present invention is used not only for the production of VLSI, but also for general IC production, further for the production of masks, the production of printing plates such as planographic printing plates, intaglio printing plates, and the like, and the photoresist for printed wiring boards. , Solder resists, color filters or resists for liquid crystal display devices, image formation such as relief images and image duplications, photocurable inks, paints, adhesives and the like.

[0025]

EXAMPLES Specific examples of the present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Synthesis Example 1 1 liter of 270 g of m-cresol and 5 g of oxalic acid
The flask was charged into a neck flask and sealed with nitrogen. While stirring this, 172 g of 37% by weight formalin was added dropwise.
The dropping time was 30 minutes. Then, under reflux 3
Reacted for hours. Water was removed by distillation, and unreacted monomers were distilled off under reduced pressure (20 mmHg). Transfer to the vat in the dissolved state, and remove the novolac resin (dissolution rate 3
900 Å / s) 280 g was obtained.

Synthesis Example 2 345 g of m-cresol, 86 g of p-cresol, (ratio of m-cresol to all phenol components: 80 mol%), and 8 g of oxalic acid were placed in a 1-liter 4-neck flask and sealed with nitrogen. While stirring this, 242 g of 37% by weight formalin was added dropwise over 30 minutes. After reacting under reflux for 5 hours, novolak resin (dissolution rate 2700Å / s) was taken out in the same manner as in Synthesis Example 1. The yield was 398 g.

Synthesis Example 3 259 g of m-cresol, 173 g of p-cresol,
(Ratio of m-cresol to total phenol component 60
Mol%) and 12 g of oxalic acid were placed in a 1-liter 4-neck flask and sealed with nitrogen. While stirring, 211 g of 37% by weight formalin was added dropwise over 30 minutes and reacted under reflux for 5 hours. Then, the novolak resin (dissolution rate 2700Å / s) was taken out in the same manner as in Synthesis Example 1. The yield was 352g. In the above synthesis example,
All dissolution rates were measured using a dissolution rate monitor (manufactured by Perkin Elmer).

Example 1 2 g of the novolak resin synthesized in Synthesis Example 1, 0.3 g of Cymel (registered trademark) 300 (manufactured by Mitsui Cyanamide Co., Ltd., main component: hexamethoxymethylmelamine), Tris (2,3)
0.1 g of -dibromopropyl) isocyanurate and 0.2 g of N-phenyl-1-naphthylamine were dissolved in 6 g of methyl methoxypropionate to prepare 0.2 of Teflon.
A photoresist composition was prepared by filtering with a μm filter. This photoresist composition was applied on a silicon wafer having a diameter of 5 inches to a thickness of 1 μm using a spin coating device (Mikasa 1H-2D). It was dried on a hot plate at 100 ° C. for 90 seconds and exposed by i-line using an i-line stepper with NA = 0.5. Thereafter, PEB was carried out at 100 ° C. for 60 seconds on a hot plate, and then developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution at room temperature for 60 seconds. When the obtained resist image was observed by SEM, the cross-sectional shape of the obtained pattern was rectangular and good, and the line width was 0.3.
It was resolved to 4 μm.

Example 2 A resist composition was prepared in the same manner as in Example 1 except that the novolak resin synthesized in Synthesis Example 2 was used, and a resist pattern was prepared and then observed by SEM. The cross-sectional shape of the obtained pattern is rectangular and good,
The line width was also resolved up to 0.40 μm.

Comparative Example 1 A resist composition was prepared in the same manner as in Example 1 except that the novolak resin synthesized in Synthesis Example 3 was used, and a resist pattern was prepared and observed by SEM. The cross-sectional shape of the obtained pattern was not rectangular and was defective, and the line width could be resolved only up to 0.5 μm.

[0031]

EFFECT OF THE INVENTION The negative photosensitive composition of the present invention does not swell at the time of development, has sensitivity to ultraviolet light, and can obtain a good pattern profile with high resolution. As a result, it is particularly useful as a photoresist for semiconductor integrated circuits.

Claims (2)

[Claims] 1. In a negative photosensitive composition containing an alkali-soluble resin, a cross-linking agent that acts on the alkali-soluble resin under acidic conditions, and an acid generator, 75 mol% or more of the alkali-soluble resin is m- A negative photosensitive composition, which is a novolac resin synthesized from cresol phenols and aldehydes. 2. The dissolution rate of the alkali-soluble resin in a 2.38 wt% aqueous solution of tetramethylammonium hydroxide at 25 ° C. is 250 to 20,000 Å / s.
The negative photosensitive composition according to claim 1, wherein