JPH06240230A - Light absorber for i-line - Google Patents

Abstract

PURPOSE:To obtain a light absorber excellent in sensitivity to i-line of a mercury lamp by using a coumarin deriv. having a specific structure. CONSTITUTION:A light absorber for i-line is a coumarin deriv. of the formula (wherein R is an acyl group, an alkoxycarbonyl group, or an aryl group). A semiconductor circuit board with an excellent resolution can be produced using this light absorber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an i-ray light absorber comprising a hydroxycoumarin derivative.

[0002]

2. Description of the Related Art In a semi-derivative integrated circuit fabrication technique, when a substrate has a step structure or unevenness in flatness, a light absorber is mixed in a photoresist film to prevent irregular reflection at the step portion or the uneven surface portion. A technique for preventing a decrease in resolution caused by the above and improving resolution is generally adopted.
Further, in order to prevent the phenomenon of resolution deterioration due to standing waves that occurs when a multi-layer resist layer is provided, mixing of a light absorbing agent is also utilized. A light absorber suitable for such a technique is well soluble in a solvent used for a photoresist composition, efficiently absorbs light emitted from a mercury lamp or other light source during exposure, and is easily eluted and removed during development. ,
It is required to have properties such as not having a great influence on the decrease in sensitivity of the photoresist and having appropriate durability such as light resistance and heat resistance when used. Japanese Patent Office Sho 51
No. 37562, oil yellow, which is a kind of dispersion type monoazo dye, is a specific example of the light absorber, and is disclosed in JP-A-62-15.
No. 0244, a hemioxonol dye as a polymethine dye used for a positive photoresist, JP-A-60-203
941 for coumarin 6, JP-A-59-142538 for monoazo dye, JP-A-2-73880, JP-A-3-12.
2645 and JP-A-4-36750 describe benzylidene derivatives and the like. However, the above-mentioned materials do not fully satisfy the characteristics as an i-ray light absorber used in a photoresist, and materials having further excellent characteristics are required.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light absorbing agent having excellent characteristics for i-line of a mercury lamp.

[0004]

As a result of intensive studies, the present inventors have found that a hydroxycoumarin derivative having a specific structure represented by the following general formula (1) has good properties as a light absorber for i-line. It was found that they had the following, and completed the invention.

Embedded image (1) In the above formula, R represents an acyl group, an alkoxycarbonyl group, or an aryloxycarbonyl group. Here, the acyl group represents an alkylcarbonyl group or an arylcarbonyl group, and specific examples thereof include an unsubstituted alkylcarbonyl group such as an acetyl group, a propionyl group and a butyryl group; a methoxyethylcarbonyl group and a methoxycarbonylmethylcarbonyl group. An alkylcarbonyl group substituted with an alkoxy group or an alkoxycarbonyl group; a benzoyl group, a 4-methylbenzoyl group,
3-methylbenzoyl group, 4-methoxybenzoyl group,
There are arylcarbonyl groups such as 2,4-dimethylbenzoyl groups. Specific examples of the alkoxycarbonyl group include linear or side chain alkyloxycarbonyl groups such as methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, n-butyloxycarbonyl group, t-butyloxycarbonyl group and benzyloxy group. A substituted alkyloxycarbonyl group such as a carbonyl group may be mentioned. Specific examples of the aryloxycarbonyl group include a phenyloxycarbonyl group, a 4-methylphenyloxycarbonyl group, a 4-methoxyphenyloxycarbonyl group and the like.

The light absorber according to the present invention (hereinafter referred to as this material) is ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, cyclohexanone,
Methyl isobutyl ketone, butyl acetate, lactic acid ethyl ester, etc. are easily soluble in organic solvents used for photoresists, and are mixed with the resin from the beginning, or the above-mentioned solvent is added to the resin solution prepared in advance. A photoresist composition containing a light absorber can be easily prepared by adding a solution of the present material dissolved in. This composition is applied on a silicon wafer so as to have a desired film thickness and prebaked at 60 to 100 ° C. to form a resist film. As a coating method, an appropriate method such as dipping, spin coating, spraying or roller is adopted.
The maximum content of this material is about 340-375n in methanol.
m, in the resist film, shifted to the long wavelength side by about 10 to 30 nm, and the absorption band extends from about 300 to 430 nm. Therefore, the i-line (365 nm) of the mercury lamp is efficiently absorbed. Therefore, when the i-line exposed by the stepper reaches the stepped portion of the substrate through the resist layer, the diffused reflection light in this portion is well absorbed, and it is effective to irradiate light to the area other than the circuit pattern portion for exposure. It is possible to prevent this and to accurately draw the desired initial circuit pattern on the substrate. In addition, this material has a relatively large molecular extinction coefficient (1
Has 0 ⁴ orders), you can reach the intended purpose with a small amount of the added amount. 0.1 to 15 weight percent, preferably 0.5 to the solid content of the photosensitive composition.
A loading of ~ 5 percent is suitable. In addition, this material has a hydroxy group at the 7-position of the benzene ring of the coumarin skeleton.
Since it is a coumarin derivative having a specific substituent at the position,
It is easily soluble not only in the positive type but also in the negative type photoresist as well as the above-mentioned organic solvents and the organic alkaline aqueous solution such as tetramethylammonium hydroxide and the inorganic alkaline aqueous solution represented by sodium hydroxide. It is used and can be developed quickly and easily.

Next, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples. Specific examples of the coumarin derivative of the present invention include the following compounds.

Embedded image Compound 1

Embedded image Compound 2

Embedded image Compound 3

Embedded image Compound 4

Embedded image Compound 5

Embedded image Compound 6

Embedded image Compound 7

Embedded image Compound 8

The coumarin derivative represented by the general formula (1) of the present invention is obtained by condensing 2,4-dihydroxybenzaldehyde and an acetic acid ester derivative having a substituent at the α-position in the presence of a base catalyst in an inert solvent by a conventional method. It can be synthesized by

Reference Example 1 Synthesis of Compound 1 A 140 ml alcohol solution containing 7 g of 2,4-dihydroxybenzaldehyde, 6.5 g of acetoacetic acid ethyl ester and 1 ml of piperidine is heated under reflux for 5 hours. After the reaction was completed, 3 ml of acetic acid was added, the alcohol was distilled off, and the obtained solid substance was washed with hexane for crystallization to give 6 g of a crude product.
To get This product is recrystallized twice from alcohol to obtain 3 g of a purified product. This product has λmax in methylene chloride
356 nm, 388 nm in novolac resin, melting point 23
It is a fluorescent pale yellow compound showing 2 ° C. Other compounds were similarly synthesized.

[0008]

EXAMPLE An ethylene glycol monoethyl ether acetate liquid prepared by dissolving 2% by weight of the material compound in a positive photoresist composition containing a 1,2-naphthoquinonediazide compound and a phenol novolak resin as main components was dissolved. In addition, a photosensitive composition was prepared. This composition was spin-coated on a stepped silicon wafer having an aluminum layer of 1 μm and dried at 80 ° C. to form a resist film having a thickness of 1.5 μm. Pass this through a photomask and use an i-line stepper to 4
It was exposed for 5 seconds and developed with a 2.38 percent aqueous solution of tetramethylammonium hydroxide. The resolution results are summarized in Table 1. As is clear from Table 1, the light absorber according to the present invention exhibits a high resolution of 1 μm or less.

[Table 1]

[0009]

The light absorber according to the present invention has a solvent special property, developability, and a property required for preparing a photoresist composition.
It is excellent in various properties such as absorption characteristics, heat resistance and light resistance. By using this material, it is possible to produce a semiconductor circuit board having excellent resolution.

Claims (1)

[Claims] 1. An i-ray light absorber comprising a coumarin derivative represented by the following general formula (1): (1) In the above formula, R represents an acyl group, an alkoxycarbonyl group, or an aryloxycarbonyl group.