Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2000-10-31
2003-11-25
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S170000, C430S171000, C430S189000
Reexamination Certificate
active
06653043
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to active particles that are useful for forming minute patterns such as semiconductor integrated circuits using, for example, ultraviolet rays or far-ultraviolet rays and used in combination with a photosensitizer; a photosensitive resin composition (resist composition) containing the same; and a process for forming a pattern using the composition.
BACKGROUND OF THE INVENTION
With rises in the integration level and performance of semiconductor integrated circuits, there has been the demand for resists with better resolution (patterns in submicron order, quartermicron order, or smaller). To meet such demand, improvement of resolution, as well as resists themselves, by employing dry developing has been proposed. For example, in the case where the wavelength of light is in the neighborhood of the resolution limit, it is proposed that, utilizing the fact that a silicon-containing resin is highly resistant to oxygen plasma, the resolution is improved by dry-developing a thin silicon-containing resist through oxygen plasma. This process, however, has the drawbacks that synthesis of polysiloxane-based resists rendered photosensitive becomes complicated and thus results in a rise in cost and that it is difficult to control, with good repeatability, the content of silicon giving a large influence on oxygen plasma resistance. The silicon content and the performance of a resist (sensitivity, resolution) are generally in a conflicting relation. That is, increasing the silicon content improves oxygen plasma resistance but deteriorates the performance of a resist. Decreasing the silicon content improves the performance of a resist (sensitivity, resolution) but leads to degradation of oxygen plasma resistance. For such reasons, improving the performance of a resist while keeping its oxygen plasma resistance level high is difficult. In addition, in such resists, the contrast (difference in solubility in a developer) between exposed areas and non-exposed areas is insufficient to improve the resolution.
A photosensitive paste being a photosensitive resin filled with an inorganic compound such as a silicon compound in the form of microfine particles has also been known. Improvement of its oxygen plasma resistance requires the paste to be filled with a larger amount of the inorganic microfine particles. However, an increase in the content of the inorganic microfine particles, due to absorption, reflection, or scattering of light by the particles, results in deterioration in sensitivity and resolution.
On the other hand, there have been known compositions comprising an alkali-soluble novolak resin and a diazonaphthoquinone derivative as resists for semiconductors. Utilizing the characteristic that a diazonaphthoquinone group is decomposed upon irradiation with 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, these photosensitive resin compositions have been used as positive resists. However, when used in combination with the silicon-containing inorganic microfine particles described above, the sensitivity is largely degraded. The use of silicasol as the inorganic microfine particles improves the transmittance of light with which to irradiate the resist but cannot improve the resolution.
As a means for improving the sensitivity and resolution even with an large inorganic component content, Japanese Patent Application Laid-Open No. 194491/1999 proposes a photosensitive resin composition composed of a photosensitive organic oligomer or polymer, a hydrolytic polymerizable organic metal compound or its condensate, and an inorganic filler having a functional group.
Japanese Patent Application Laid-Open No. 158235/1993 discloses a resist composition composed of: a resist being a mixture of cresolnovolak and a naphthoquinonediazide sulfonate; and silicasol added thereto.
In these resists, however, only not so large a difference in dissolution rate can be made between exposed portions and non-exposed portions and therefore the resolution can be improved only to a limited extent.
In the novolak-series semiconductor resist, the most conventional method for achieving miniaturization or minuter patterns is to use an exposure light of a shorter wavelength. For example, instead of using g-ray (wavelength: 436 nm) or i-ray (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 in the production of semiconductor integrated circuits using g-ray or i-ray leads to considerable deterioration in sensitivity and resolution even with KrF excimer laser or ArF excimer laser because of the absorption of light by 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, exposing devices such as light sources and lens systems, 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.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide active particles capable of, when incorporated into a photosensitive resin, making the difference in dissolution rate between exposed areas and non-exposed areas larger while keeping the oxygen plasma resistance of a photosensitive layer high, and useful in forming patterns with high sensitivity and high resolution; a photosensitive resin composition containing the same; and a process for forming a pattern using the resin composition.
Another object of the present invention is to provide a photosensitive resin composition capable of improving, even in the case with existing equipment, heat resistance as well as sensitivity and resolution; a process for producing the same; and a process of forming a pattern using the resin composition.
Still another object of the present invention is to provide a process for improving the sensitivity and resolution of the photosensitive resin.
The inventors of the present invention made intensive studies to achieve the above objects and finally found that addition of active particles, which accelerates the solubility of exposed area in a developer (e.g., alkalis) and interact with a photosensitizer with the aid of a developer (e.g., alkalis) in non-exposed areas, to a resin composition comprised of a base resin and a photosensitizer (e.g., novolak-series phenolic resin/quinonediazide) increases the difference in the rate of dissolution between exposed areas and non-exposed areas, making it possible to form patterns with high sensitivity and high resolution. The present invention was accomplished based on the above finding.
That is, the active particles of the present invention are for use in combination with a photosensitizer contained in a photosensitive resin, each comprising a particulate carrier and an aromatic unit which is directly or indirectly bonded thereto and, with the aid of a developer (e.g., alkalis), becomes active (e.g., interactive, reactive) to the photosensitizer. The active particles may have a structure in which, via a coupling agent, a particulate carrier is bonded to an aromatic unit having a phenolic hydroxyl group. The aromatic unit, for the purpose of enhancing the interactivity with a photosensitizer with the aid of a developer (e.g., alkalis), may have no substituent at least either in the o-position or p-position in relation to the phenolic hydroxyl group. The mean particle size of the particulate carriers may be about 1 to 100 nm. Such active particles react with a photosensitizer (e.g., qui
Baxter Janet
Kansai Research Institute, Inc.
Pillsbury & Winthrop LLP
Thornton Yvette C.
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