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
2000-04-03
2002-11-12
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
C430S914000, C430S919000, C430S921000
Reexamination Certificate
active
06479210
ABSTRACT:
TECHNICAL FIELD
This invention relates to a chemically amplified resist composition for use in manufacturing integrated circuit elements or the like. More particularly, it relates to a chemically amplified resist composition which is sensitive to radiation such as UV rays, deep UV rays, electron beams, X-rays or the like and which can give a good pattern profile with high sensitivity and high resolution.
BACKGROUND ART
In the art of fine processing technology such as manufacture of integrated circuit elements, radiation sensitive resist materials showing high resolution have been desired as the degree of integration is increasing. In recent years, a pattern rule of the order of sub-quarter micron has been demanded. In order to comply with the demand, exposure equipment for use in fine processing, particularly photolithography, are being equipped with a light source emitting light of an increasingly shorter wavelength. Namely, the light sources have been changed from g-line (436 nm) and i-line (365 nm) to KrF excimer laser (246 nm in deep UV region) and ArF excimer laser (193 nm also in deep UV region). As radiation sensitive resist materials suited for forming patterned resists by exposing with such short wavelength light, there have been developed chemically amplified resists which can create images with less amount of light absorption and which show high sensitivity, and various such resists have been reported. The chemically amplified resists are resists which give a pattern through the phenomenon that acids are generated upon exposure, and the acids in turn cause chemical reaction (e.g., change in polarity, cleavage of chemical bond, cross-linking reaction, etc.) based on their catalytic activity in the resist coating to cause change in solubility of the radiation-exposed areas for an alkaline developer solution. As such chemically amplified resist materials, there are known, for example, those chemically amplified resist materials which are reported by Ito et al. and which comprise a hydroxystyrene polymer wherein part of phenolic hydroxyl groups are protected by t-butyloxycarbonyl (t-BOC) group and a compound which generates an acid such as triphenylsulfonium hexafluoroantimonate [H. I to and C. G. Wilson, Polym. Eng. Sci., vol.23, 1012(1983)]. In the resist materials, acids are generated in exposed areas by exposure, and the acids function, after exposure, to catalytically eliminate and release t-butoxycarbonyl (t-BOC) group upon baking at a temperature of, for example, above 50° C. (post exposure baking; PEB), thus producing hydroxystyrene capable of being soluble in an alkaline developer solution. If acids are generated even in a slight amount during exposure, several t-butyloxycarbonyl groups can be eliminated by the catalytic chain reaction. This elimination or releasing reaction proceeds catalytically, and hence the chemically amplified resist materials can show high sensitivity when exposed to deep UV rays. With respect to the chemically amplified resist materials, various protective groups known in the field of organic synthesis have been tried and reported for obtaining positive-working deep UV ray photoresists, following the t-butyloxycarbonyl group reported by Ito et al.
As at present known positive-working resist compositions, there are those which contain (a) an alkali-insoluble or slightly alkali-soluble resin which is protected by the group capable of being eliminated and released by acid (hereinafter referred to as “acid-decomposable group”) and which becomes alkali-soluble when the acid-decomposable group is released (hereinafter referred to as “resin containing acid-decomposable groups”) and (b) a compound capable of generating acid upon exposure with radiation (hereinafter referred to as “acid-generator”) and, optionally, an auxiliary component (c) a compound which controls alkali solubility of the resin (a) containing acid-decomposable groups and which is decomposed in the presence of an acid to undergo reduction or loss of the effect of controlling alkali solubility of the resin containing acid-decomposable groups (hereinafter referred to as “dissolution inhibitor”).
As the acid-generator for the chemically amplified resist composition, there are known onium salt compounds, sulfone compounds, sulfonate compounds, etc. Onium salt compounds have such a strong ability of suppressing dissolution of resist coating that unexposed portions of the radiation sensitive material show a smaller dissolution property for a developer solution, though they generates a comparatively strong acid upon being exposed. Therefore, the chemically amplified resist containing an onium salt compound can provide resist pattern with high resolution. On the other hand, it has defects that it is liable to form standing waves on a developed resist pattern and, under some process atmosphere, generate an insoluble layer on the surface of the resist layer which forms an overhung profile, called T-top. Further, the onium salt compound has the defect that it has such a poor solubility in resist solvents that its amount of addition to a resist is limited. On the other hand, sulfone compounds and sulfonate compounds show a high solubility in resist solvents and less ability of suppressing dissolution of resist coating into a developer solution, but solubility of decomposition products thereof after exposure is better than that of the onium salt compounds. Hence, in comparison with the onium salt compounds, the sulfone compounds and the sulfonate compounds enable one to increase contrast and form less standing waves on developed resist patterns. In addition, since they generate comparatively weak acids, they are advantageous from the point of view of environmental pollution, too. However, they have the defect that they provide a large dimensional difference between line width in a dense pattern area and that in an isolated pattern area due to their high solubility.
As is described above, various chemically amplified resist compositions are known as resist materials sensitive to UV rays, deep UV rays, electron beams, X-rays or the like, and various acid-generators for use in them are also known. However, all of the acid-generators have some defects and do not show satisfactory result.
An object of the present invention is to provide a method of forming a pattern not having the above-described defects.
That is, an object of the present invention is to provide a chemically amplified resist composition which shows a high sensitivity and a high resolution, which shows excellent process adaptability and process stability, which has no dependence on processing conditions and which can form a resist image with good pattern profile.
DISCLOSURE OF THE INVENTION
As a result of intensive investigations, the inventors have found that a positive-working chemically amplified resist composition which can satisfy the above-described requirements can be obtained by using, as the acid-generators, at least one onium salt compound in combination with at least one of the sulfone compounds and the sulfonate compounds and, optionally, a specific basic compound, thus having completed the present invention based on the findings.
That is, the subject of the present invention is a chemically amplified resist composition which contains an organic material having a substituent or substituents capable of being released in the presence of an acid and a compound capable of generating an acid upon exposure with radiation (acid-generator) and which undergoes change in solubility for an alkaline developer solution in radiation-exposed areas thereof due to the catalytic action of the acid generated by exposure with radiation to form a pattern, said compound capable of generating an acid by exposure with radiation comprising both at least one onium salt compounds and at least one of sulfone compounds and/or sulfonate compounds.
In addition, the subject of the present invention is the chemically amplified resin composition as described above, which further contains at least one of basic compounds selected from among
Funato Satoru
Kinoshita Yoshiaki
Yamaguchi Yuko
Ashton Rosemary
Clariant Finance (BVI) Limited
Jain Sangya
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