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
2000-02-28
2002-05-28
Ashton, Rosemary (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
C430S270100, C430S326000
Reexamination Certificate
active
06395453
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel photoresist composition, which is suitable for fine processing techniques using photolithography, and a patterning method.
2. Related Art
While a finer pattern rule has recently been required with the use of LSI's of higher integration degree or higher processing speed, far ultraviolet ray lithography has been recognized as a promising fine processing technique of the next generation. This far ultraviolet ray lithography enables processing of lines having a width of 0.3 &mgr;m or less, and it can form a pattern having sides substantially perpendicular to a substrate, when a photoresist composition of low light absorption is used.
Further, techniques utilizing highly luminous KrF or ArF excimer lasers as a source of far ultraviolet ray are recently attracting much attention. In view of this, chemical amplification type photoresist compositions utilizing an acid as a catalyst have been developed. However, with the progress of techniques for large-scale production, more stable photoresist compositions with smaller fluctuation of sensitivity during the storage or use thereof have been required.
However, as a drawback of the chemical amplification type photoresist compositions, there has hitherto been recognized a problem that, when the standing time from the exposure to PEB (Post Exposure Bake) becomes longer, acid generated by the exposure on the surface of the photoresist film reacts with basic compounds in the air to be inactivated, and thus only upper parts of the formed line patterns become thick (referred to as “T-top shape” hereinafter).
In order to solve this problem, Japanese Patent Unexamined Publication No. 9-297401 proposed addition of an &agr;,&bgr;-unsaturated carboxylic acid ester such as methacrylic esters and acrylic acid esters, or an &agr;,&bgr;,&agr;′,&bgr;′-unsaturated ketones such as phorone. The addition of such an &agr;,&bgr;-unsaturated carboxylic acid ester or &agr;,&bgr;,&agr;′,&bgr;′-unsaturated ketone is in fact effective for the prevention of the T-top shape to some extent, but there has been a problem that it does not provide sufficient effect on the prevention of the sensitivity fluctuation of photoresist compositions.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of the aforementioned problems, and its object is to provide a photoresist composition showing excellent stability of sensitivity even after long term storage or exposure to environmental temperature variation, and a patterning method using it.
The present invention has been accomplished in order to achieve the aforementioned object, and provides a photoresist composition containing at least an &agr;,&bgr;-unsaturated ketone compound.
The photoresist composition containing at least an &agr;,&bgr;-unsaturated ketone compound is unlikely to be affected by long term storage or environmental temperature variation upon use. Therefore, it can be a photoresist composition of excellent stability of sensitivity.
In the aforementioned photoresist composition, the &agr;,&bgr;-unsaturated ketone compound is preferably one represented by the following general formula (1).
In the formula, R
1
and R
2
independently represent a linear alkyl group having 1-10 carbon atoms, a branched alkyl group or a cycloalkyl group having 3-10 carbon atoms, or an aryl group having 6-14 carbon atoms.
The photoresist composition containing at least an &agr;,&bgr;-unsaturated ketone compound represented by the aforementioned general formula (1) is surely unlikely to be affected by long term storage or environmental temperature variation upon use. Therefore, it can be a photoresist composition of more excellent stability of sensitivity.
Further, the photoresist composition may be a chemical amplification type photoresist composition for which exposure is performed with a high energy ray having a wavelength of 500 nm or less, X-ray or electron ray.
The photoresist composition of the present invention is particularly advantageous when it is used as a chemical amplification type composition for which exposure is performed with a high energy ray having a wavelength of 500 nm or less, X-ray or electron ray.
The present invention also provides a patterning method comprising at least the following steps:
(i) a step of application of the aforementioned photoresist composition of the present invention to a substrate,
(ii) a step of, after a heat treatment, exposure with a high energy ray having a wavelength of 500 nm or less, X-ray or electron ray through a photomask, and
(iii) a step of development with a developer.
The patterning method comprising at least the above steps of (i) to (iii) can prevent variation of sensitivity due to long term storage, fluctuation of environmental temperature upon use and so forth, and variation of processed pattern size, because the resist composition is excellent in stability of sensitivity. Therefore, the method is particularly suitable for precise fine processing.
The photoresist composition of the present invention is unlikely to be affected by the environmental temperature during storage and upon use, and excellent in stability of sensitivity. Therefore, it enables stable and easy formation of fine patterns perpendicular to a substrate by exposure with a far ultraviolet ray having a wavelength of 254-193 nm, high energy ray such as excimer laser ray, X-ray, electron ray or the like, and hence it is suitable for fine processing techniques in large scale production processes of semiconductor devices and so forth.
DESCRIPTION OF THE INVENTION AND EMBODIMENTS
Embodiments of the present invention will be explained hereinafter. However, the present invention is not limited to them.
The inventors of the present invention eagerly studied in order to attain the aforementioned object. As a result, they found that use of the &agr;,&bgr;-unsaturated ketone compound as an additive of photoresist compositions provided the most excellent effect on stability of sensitivity after long term storage or variation of environmental temperature, and examined various conditions for the above finding. Thus, they accomplished the present invention.
Hereafter, the most characteristic feature of the present invention, the &agr;,&bgr;-unsaturated ketone compound, which is to be added to the photoresist composition, will be explained in detail.
Examples of the &agr;,&bgr;-unsaturated ketone compound include those represented by the following general formula (1).
In the formula, R
1
and R
2
independently represent a linear alkyl group having 1-10 carbon atoms, a branched alkyl group or cycloalkyl group having 3-10 carbon atoms, or an aryl group having 6-14 carbon atoms.
R
1
and R
2
represent a linear alkyl group having 1-10 carbon atoms, preferably 1-7 carbon atoms, a branched alkyl group or cycloalkyl group having 3-10 carbon atoms, or an aryl group having 6-14 carbon atoms. Examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, hexyl group, heptyl group, nonyl group, decyl group, phenyl group, cyclopentyl group, cyclohexyl group, norbornyl group, adamantyl group and so forth.
Specific examples of the &agr;,&bgr;-unsaturated ketone compound represented by the aforementioned general formula (1) include 3-buten-2-one, 4-methyl-3-penten-2-one, 3-methyl-3-buten-2-one, pent-3-en-2-one, 3-octen-2-one, 4-isopropyl-3-buten-2-one, 3-hepten-2-one, 2-hepten-4-one, 3-octen-2-one, 5-isopropyl-2-hepten-4-one, 3-nonen-2-one, 3-nonen-5-one, 3-decen-2-one, 4-phenyl-3-buten-2-one, chalcone, ionone and so forth. Among them, 3-nonen-2-one, 3-octen-2-one and 3-hepten-2-one are particularly preferred.
The photoresist composition to which the aforementioned &agr;,&bgr;-unsaturated ketone compound is added may be either of positive type or negative type, and composition of the photoresist composition except for the &agr;,&bgr;-unsaturated ketone compound may be a known one.
Whe
Kaneko Tatsushi
Koizumi Kenji
Watanabe Satoshi
Yanagi Yoshitaka
Ashton Rosemary
Oliff & Berridg,e PLC
Shin-Etsu Chemical Co. , Ltd.
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