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
2000-01-28
2001-08-07
Ashton, Rosemary E. (Department: 1725)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C522S148000
Reexamination Certificate
active
06270941
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a positive silicone-containing photosensitive composition for exposure by radiation of ultraviolet rays, far ultraviolet rays, X-rays, electron beams, molecular beams, gamma-rays and synchrotron radiation. More specifically, the present invention relates to a positive silicone-containing photosensitive composition for forming fine patterns particularly having high resolution, sensitivity, giving resist of a rectangular cross section, and having broad processing tolerance, which are used for producing, for example, circuit boards, etc., in the producing process of a semiconductor such as IC and the like.
The positive silicone-containing photosensitive composition according to the present invention can be used in the following processes. For example, the positive silicone-containing photosensitive composition according to the present invention is coated on a substrate such as a semiconductor wafer, glass, ceramic or metal, or these substrates having provided thereon a reflection preventing layer or an organic layer in a thickness of from 0.01 to 3 &mgr;m by a spin coating method or a roller coating method. Subsequently, the coated layer is heated and dried, and a circuit pattern or other pattern is printed on the layer by, e.g., irradiation which actinic rays through an exposure mask, and then developed to form a positive image. Further, the substrate can be etched with this positive image as the mask to form the pattern on the substrate. Typical applications of the positive silicone-containing photosensitive composition are manufacture of semiconductors such as IC and the like, manufacture of circuit boards for liquid crystals and thermal heads, and other photo fabrication processes.
BACKGROUND OF THE INVENTION
With the higher integration of LSI, it is apparent that conventional monolayer resist systems have already reached the utmost limit of resolution hence a method of forming a high shape ratio having a large layer thickness but a fine pattern has been proposed by employing a multilayer resist system. That is, an organic polymer thick layer is formed as a first layer and a resist thin layer is provided thereon as a second layer, and the second resist material layer is irradiated with high energy radiation to thereby perform development. This method aims at obtaining a pattern having high rectangular property by oxygen plasma etching (O
2
RIE) the first organic polymer layer anisotropically using the positive image obtained above as the mask (see Lin,
Solid State Technology
, Vol. 24, p. 73 (1981)).
In this case, the second resist material layer should be highly resistive to O
2
RIE hence it is suggested to use a silicon-containing polymer as the second layer.
Further, Bowden et al., reported polytrimethylsilylbutetnyl sulfone (see
Society of Photooptical Instrumentation Engineering Abstract
, 631-01 p. 14 (1986)). However, as these resist materials are low in a silicon content and silicon is introduced into the side chain, the resistance to oxygen plasma is not sufficient and cannot be used as the mask of the etching of the first organic polymer layer. Further, a non-swelling type resist capable of alkali development is necessary for forming a pattern of high resolution.
Various attempts have been done for the development of resists which have oxygen plasma resistance and alkali development suitability, and they have been partly used for g-line exposure (exposure wavelength of 436 nm) or other exposure.
For example, JP-A-1-283555 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-4-36754, JP-A-4-130324 and JP-A-2-29652 can be exemplified. However, a pattern of high resolution and rectangular shape cannot be obtained by these techniques because light absorption of these resists to exposure light is too large for the formation of fine patterns of a line width of 0.3 &mgr;m or less with KrF excimer laser beams, etc.
For reducing light absorption to exposure light, solution to the problem has been attempted variously using a small amount of photoacid generator and a compound whose alkali-insoluble group is decomposed by the generated acid and becomes alkali-soluble.
These techniques are disclosed in JP-A-63-218948, JP-A-63-241542, JP-A-4-245248 and JP-A-6-184311, for instance.
However, when these techniques are applied for the formation of ultrafine patterns of a line width of 0.2 &mgr;m or less, a rectangular pattern cannot be obtained because the layer thickness extremely decreases after development as even the unexposed area is partly exposed due to the diffraction of light. Further, dimensional fluctuation becomes large in some resists and mask dimension can hardly be reproduced in the pattern transfer to the lower layer in the next oxygen plasma process as the silicon content in the resist is low.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above-described problems and provide a photosensitive composition having high sensitivity and high resolution in semiconductor device production. Specifically, an object of the present invention is to provide a photosensitive composition which exhibits little light absorption in deep ultraviolet region and can cope with short wavelength light sources.
Another object of the present invention is to provide a positive photosensitive composition which can cope with exposure in a far ultraviolet region and have high sensitivity and high resolution in semiconductor device production.
A further object of the present invention is to provide a positive photosensitive composition which causes little film thickness loss in a fine pattern of a line width of 0.2 &mgr;m or less after development process and gives a rectangular resist.
A still further object of the present invention is to provide a positive photosensitive composition which causes less dimensional shift (dimensional fluctuation) in pattern transfer to the lower layer in oxygen plasma process and is excellent in dimensional reproduction.
Other object of the present invention is to provide a positive photosensitive composition having broad processing tolerance.
As a result of extensive investigations by the present inventors taking the above various characteristics into consideration, the present invention has been accomplished. That is, the objects of the present invention can be attained by the following constitutions.
(1) A positive silicone-containing photosensitive composition which comprises:
(a) a water-insoluble and alkali-soluble polymer having a structure represented by the following formula (I) and/or (II)
wherein X represents a group selected from the group consisting of a —C(═O)—R group, a —CH(OH)—R group, and a carboxyl group, and a plurality of X's may be the same or different; R represents a hydrogen atom or a hydrocarbon group which may have a substituent; R′, R″, R″′, R″″ and R″″′, which may be the same or different, each represents a group selected from the group consisting of a hydroxyl group, and an alkyl, cycloalkyl, alkoxyl, alkenyl, aralkyl and phenyl groups each of which may have a substituent; Y represents an alkyl group, an alkoxyl group or a siloxyl group; R
0
represents a group selected from the group consisting of a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group and a substituted or unsubstituted aromatic hydrocarbon group; 1, m, n and q each represents 0 or a positive integer; and p represents a positive integer;
(b) a compound which generates an acid upon irradiation with actinic rays or radiation, and
(c) a polymer which has a repeating unit containing a group represented by formula (III), (IV) or (V) at the side chain, and shows the enhanced solubility in an alkaline developing solution by the action of an acid:
wherein R
a
, R
b
, and R
c
each represents a hydrogen atom, or a hydrocarbon group which may have a substituent; and s represents an integer of 2 or more.
(2) A positive silicon-contain
Ashton Rosemary E.
Fuji Photo Film Co. , Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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