Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
1999-08-18
2002-08-27
Chu, John S. Y. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S191000, C430S192000, C430S193000
Reexamination Certificate
active
06440632
ABSTRACT:
TECHNICAL FIELD
The present invention relates to photosensitive resin compositions (resists) suitable for minute-processing of semiconductors by using ultraviolet rays or far-ultraviolet rays (including excimer laser and so on), a method for producing the same, and a method for forming patterns using the same.
BACKGROUND ART
There have been known compositions comprising an alkali-soluble novolak resin and a diazonaphthoquinone derivative as resists for semiconductors. These photosensitive resin compositions have been used as positive resists utilizing the characteristic that a diazonaphthoquinone group is decomposed upon irradiation with a light of 300 to 500 nm wavelength to form a carboxyl group, allowing the compositions to change from an alkali-insoluble state to an alkali-soluble state.
On the other hand, with a rise in the integration level of integrated circuits of semiconductors, the integrated circuits are getting minuter and minuter in recent years, and the formation of patterns in submicron order, quartermicron order, and smaller is now demanded. The most conventional method for achieving miniaturization or minuter integrated circuits is to use an exposure light of a shorter wavelength. For example, instead of using g-line (wavelength: 436 nm) or i-line (wavelength: 365 nm) of high-pressure mercury lamps generally used, a light source of a shorter wavelength such as KrF excimer laser (wavelength: 248 nm) and ArF excimer laser (wavelength: 193 nm) of next generation have already come into practical use.
However, the use of novolak resin/diazonaphthoquinone-type positive resists having been employed for the production of semiconductor integrated circuits using g-line or i-line leads to considerable deterioration in sensitivity and resolution even with KrF excimer laser or ArF excimer laser owing to the absorption ability of the novolak resin. Therefore, the novolak resin/diazonaphthoquinone-type positive resists are lacking in practicability.
Moreover, minute processing with KrF or ArF excimer laser has a number of technical problems to be solved with respect to the choice of, for example, light sources, exposing devices such as a lens system and photosensitive materials (resists). In addition, plant investment for applying the minute processing with KrF or ArF excimer laser to the practical production of semiconductors will be a vast sum of money.
Accordingly, an object of the present invention is to provide a photosensitive resin composition capable of largely improving sensitivity and resolution even with an existing apparatus (particularly, exposing system), a method for producing the same, and a method for forming patterns.
Another object of the present invention is to provide a photosensitive resin composition capable of largely improving the pattern profile and the focus latitude, a method for producing the same, and a method for forming patterns.
DISCLOSURE OF INVENTION
The inventors of the present invention made intensive investigations and found that the surface of a resist layer can be made hardly soluble or readily soluble by exposing the resist layer to a light of wavelength &lgr;1 or &lgr;2 through a mask patternwiese, the resist layer being composed of a combination of a first photoactive ingredient active at an absorption wavelength &lgr;1 and a second photoactive ingredient which shows high absorption at wavelength &lgr;2, and then exposing all over the patterned surface to a light of wavelength &lgr;2 or &lgr;1 (hereinafter, referred to simply as “overall-exposure”), and that a pattern having a high &ggr;-value and high resolution can be formed with high precision by developing the resist layer. The present invention has been achieved based on the above findings.
To summerize, the photosensitive resin composition of the present invention comprises a base resin and a photoactive component, and the photoactive component is constituted of a plurality of photoactive ingredients each having an absorption range at wavelength &lgr;1 or &lgr;2, the wavelengths thereof being different from each other. The base resin may be a novolak resin or polyvinylphenol-series polymer, and the photoactive component comprises a first photoactive ingredient having an absorption range at wavelength &lgr;1 and a second photoactive ingredient having an absorption range at wavelength &lgr;2. Usually, between the first and second photoactive ingredients, one of which is substantially inert at the absorption wavelength of the other. The first photoactive ingredient and the second photoactive ingredient may be a combination of, for example, a diazobenzoquinone derivative and/or diazonaphthoquinone derivative with an azide compound, a photoactive acid generator, or a photoactive acid generator and a crosslinking agent, or a combination of an azide compound and a photoactive acid generator.
The present invention includes a method for producing photosensitive resin compositions which comprises mixing a base resin with a plurality of photoactive ingredients each having an absorption range at wavelength &lgr;1 or &lgr;2, the wavelengths thereof being different from each other.
The present invention further includes a method for forming a pattern which comprises exposing the photosensitive resin composition to a light having a wavelength of either &lgr;1 or &lgr;2 to form a pattern, and exposing the entire surface of the pattern-exposed photosensitive resin composition to a light of the other wavelength.
In the present specification, “photoactive ingredients” are components generally referred to as photosensitizers, sensitizers, and so on, and are components which cause photoreactions by being activated or excited by light and take part in the formation of patterns. Regarding the photoactive ingredients, the term “wavelength” or “absorption wavelength” &lgr;1 or &lgr;2 means a wavelength at which the photoactive component is photosensitized and activated or excited by irradiation of a light of wavelength &lgr;1 or &lgr;2 and partakes in a photoreaction. Moreover, in the present specification, the term “absorption range” of a photoactive ingredient means an absorption wavelength range within which the absorption coefficient is not less than 1 (preferably not less than 10) at an exposing wavelength. The above “wavelength” or “absorption wavelength” &lgr;1 or &lgr;2 refers to an absorption range of the longest wavelength among the above absorption ranges.
BEST MODE FOR CARRYING OUT THE INVENTION
The species of the base resin can be selected according to which type of resist, positive or negative, is to be formed, and there may be exemplified phenol novolak resins, polyvinylphenol-series polymers, polymers having a non-aromatic ring such as a cycloalkyl group, polyvinyl alcohol-series polymers, acrylonitrile-series polymers, acrylamide-series polymers, polymers having a photodimerizable functional group such as cinnamoyl group and cinnamylidene group, nylon- or polyamide-series polymers, and polymerizable oligomers. When utilizing as a resist for semiconductor production, a novolak resin, a polyvinylphenol-series polymer and the like can be utilized as the base resin.
As the novolak resin, an alkali-soluble novolak resin is usually employed. When utilizing as a resist for semiconductor production, novolak resins conventionally employed in the field of resist can be used. A novolak resin can be obtained by condensing a phenol having at least one phenolic hydroxyl group in the molecule with an aldehyde in the presence of an acid catalyst. Examples of the phenol are, for example, C
1-4
alkylphenols such as phenol, o-, m-, and p-cresols, 2,5-, 3,5-, and 3,4-xylenols, 2,3,5-trimethylphenol, ethylphenol, propylphenol, butylphenol, 2-t-butyl-5-methylphenol; dihydroxybenzenes; and naphthols. Examples of the aldehyde are aliphatic aldehydes such as formaldehyde, acetaldehyde, and glyoxal; and aromatic aldehydes such as benzaldehyde and salicylaldehyde.
These phenols can be used either singly or as a combination of two or more species, and the aldehydes can also be used singly or in combination. As
Chu John S. Y.
Kansai Research Institute
Pillsbury & Winthrop LLP
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