Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Patent
1990-10-17
1993-05-18
Bowers, Jr., Charles L.
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
430165, 430193, 430197, 430325, 430326, 430907, 430910, 526280, 526283, 526308, 526309, G03F 7023, G03F 7012, C08F 3600
Patent
active
052120430
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a photoresist composition. More particularly, the present invention relates to a photoresist composition suitable for far ultraviolet or excimer laser lithography, wherein a resin soluble in an aqueous alkaline solution having units of an aliphatic cyclic hydrocarbon main frame and units derived from maleic anhydride and/or units derived from a maleimide, is used as a base resin. Such a composition is useful particularly as a resist for fine working in the field for the production of semiconductor elements.
With respect to semiconductor elements such as LSI or VLSI, the degree of their working tends to be finer year by year for the purpose of improving their performance. At present, lithography using g-line (436 nm) as the light source is widely used as a fine working technique for the production of such semiconductor elements. Even in such lithography, efforts for a higher resolution are being made to meet the need for fine working of such elements. As the main techniques presently available for a high resolution, there may be mentioned an attempt for a higher NA (numerical aperture) of a lens for reduced projection in an exposure apparatus and an attempt for a shorter wavelength of the light source for exposure from g-line to i-line (365 nm). Among them, the attempt for a higher NA of lens has already reached a level close to the limit. For the future, it will be necessary to further the attempt for a shorter wavelength of the light source for exposure and thereby to accomplish a higher resolution for lithography. With such a background, the resist will also be required to meet the requirements for a short wave light source such as far ultraviolet rays or excimer laser. Now, the applicability and problems of resists for application to lithography using such a short wave light source, will be described.
A resist is usually a composition comprising a base resin, a photosensitive agent and a solvent. Among them, as the base resin, a resin soluble in an aqueous alkaline solution is commonly employed for a resist required to have a high resolution so that both positive and negative resists can be developed with an aqueous alkaline solution to avoid a problem of swelling during the development. As such a resin soluble in an aqueous alkaline solution, a phenol resin such as a novolak resin or a polyvinylphenol is most commonly used at present. Such a phenol resin is relatively transparent in the wavelength region of g-line or i-line. However, in the wavelength region of far ultraviolet or excimer laser, such a phenol resin tends to be extremely poor in transparency, since it has aromatic rings in its structure. Therefore, if a conventional photoresist composition using a phenol resin as the base resin, is used for lithography using a short wavelength light as the light source, the incident light entered from above the resist can not reach the bottom of the resist layer, whereby the resist reaction can not uniformly be conducted in the direction perpendicular to the resist layer. As a result, with a positive resist, the development tends to be inadequate or the resist pattern tends to be trapezoid if the development is strongly conducted. On the other hand, with a negative resist, the pattern after the development tends to be reversed-trapezoid. If the wall of the resist is not vertical, the width of the resist pattern is likely to be changed in the subsequent step for etching a part of the resist (such as reactive ion etching), whereby an adverse effect is likely to be given to the circuit thereby produced. Further, with either type of resist, in order to let the light reach the bottom of the resist layer, a large quantity of exposure is required. Consequently, such a resist is not necessarily satisfactory with respect to the sensitivity.
It is an object of the present invention to provide a photoresist composition which is capable of providing excellent transparency in the wavelength regions of far ultraviolet rays and excimer laser and which has a high resolution and high sens
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Matsumura Kosaburo
Nagaoka Kyoko
Seita Toru
Todoko Masaaki
Yamamoto Takashi
Bowers Jr. Charles L.
Chu John S.
Tosho Corporation
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