Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
2000-03-07
2002-06-11
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S270100, C430S331000, C430S914000
Reexamination Certificate
active
06403288
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a resist pattern formation method. More specifically, it relates to a method of forming a resist pattern free from a development defect by maintaining the amount of reduction in film thickness after wet development at a relatively large value.
There is proposed a chemically amplified resist whose sensitivity is improved by the catalytic function of a radiation sensitive acid generating agent which generates an acid when exposed to radiation (to be referred to as “exposure” hereinafter) as a resist suitable for use with far ultraviolet radiation from a KrF excimer laser or the like, charged beams such as electron beams and X-ray radiation such as synchrotron radiation.
As a problem special to this chemically amplified resist, it has been pointed out that its resist pattern is changed in line width or T-shaped according to a post-exposure delay (to be referred to as “PED” hereinafter) which is a time from exposure to a heat treatment. In recent years, there have been proposed various chemically amplified resists which can be applied in the production of devices, including a chemically amplified radiation sensitive resin composition which comprises a polymer consisting of a hydroxystyrene-based recurring unit, a t-butyl (meth)acrylate recurring unit and a recurring unit for reducing the solubility in an aqueous-alkaline developer of the polymer after exposure (JP-A 7-209868) (the term “JP-A” as used herein means an “unexamined published Japanese patent application”).
Along with a reduction in the design rule of a device to a level of sub-half micron or less, attention has been paid to a new problem for the chemically amplified resist that development defects such as an undeveloped portion of a fine pattern, a fallen pattern and changes in line width (to be referred to as “development defects” hereinafter) are produced by “differences” in solubility in a developer among exposed portions. Since development defects greatly reduce device yield, needs for a chemically amplified positive radiation sensitive resin composition free from such development defects have been arising.
It is an object of the present invention to provide a resist pattern formation method.
It is another object of the present invention to provide a method of forming a resist pattern which is not changed in line width or T-shaped by PED, is free from development defects and does not impair basic performance (resolution, DOF) from a chemically amplified positive radiation sensitive resin composition.
It is still another object of the present invention to provide a method of forming a resist pattern from a chemically amplified positive radiation sensitive resin composition which has high sensitivity to various types of radiation including far ultraviolet radiation from a KrF excimer laser or the like, charged beams such as electron beams and X-ray radiation such as synchrotron radiation (small amount of exposure energy).
Other objects and advantages of the present invention will become apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are attained by a method of forming a resist pattern from a chemically amplified positive radiation sensitive resin composition, wherein the film thickness of an unexposed portion of a resist film formed from the chemically amplified positive radiation sensitive resin composition after wet development is 100 to 400 Å smaller than that before wet development.
Secondly, the above objects and advantages of the present invention are attained by a method of forming a resist pattern from a chemically amplified positive radiation sensitive resin composition, wherein a resist film formed from the chemically amplified positive radiation sensitive resin composition is wet developed at both a temperature and a time enough to ensure that the thickness of an unexposed portion of the resist film after wet development is 100 to 4 Å smaller than that before wet development.
Thirdly, the above objects and advantages of the present invention are attained by use of a resist film which is formed from a chemically amplified positive radiation sensitive resin composition and whose thickness of an unexposed portion after wet development is 100 to 400 Å smaller than that before wet development as a resist film for forming a resist pattern.
The present invention will be described in detail hereinunder.
The chemically amplified positive radiation sensitive resin composition used in the present invention is preferably a composition comprising (A) a resin which contains an acid dissociable group and whose solubility in an aqueous-alkaline developer increases along with the dissociation of the acid dissociable group with an acid, and (B) a radiation sensitive acid generating agent which reacts to various types of radiation including far ultraviolet radiation from a KrF excimer laser or the like, charged beams such as electron beams, and X-ray radiation such as synchrotron radiation and generates an acid upon exposure.
(A) Resin
The resin (A) in the present invention which is insoluble or hardly soluble in an aqueous-alkaline developer is a resin which contains one or more acid dissociable groups and whose solubility in an aqueous-alkaline developer increases along with the dissociation of the acid dissociable group with an acid (to be referred to as “acid dissociable group-containing resin (A)” hereinafter).
The acid dissociable group-containing resin (A) is a resin which is insoluble or hardly soluble in an aqueous-alkaline developer itself and has such a structure that the hydrogen atom of an acidic functional group in an aqueous-alkaline developer soluble resin having at least one acidic functional group such as a phenolic hydroxyl group or carboxyl group, for example, an aqueous-alkaline developer soluble resin having at least one recurring unit selected from the group consisting of recurring units represented by the following formulas (1) to (4) is substituted by at least one -acid dissociable group which can be dissociated in the presence of an acid.
In the formula (1), R
1
is a hydrogen atom or methyl group, R
2
is a halogen atom or monovalent organic group having 1 to 6 carbon atoms, and n is an integer of 0 to 3.
In the formula (2), R
3
is a hydrogen atom or methyl group.
In the formula (4), R
4
to R
8
are each independently a hydrogen atom or linear or branched alkyl group having 1 to 4 carbon atoms.
The acid dissociable group in the acid dissociable group-containing resin (A) is a substituted methyl group, 1-substituted ethyl group, 1-substituted propyl group, 1-branched alkyl group, silyl group, germyl group, alkoxycarbonyl group, acyl group and cyclic acid dissociable group.
Examples of the substituted methyl group include methoxymethyl group, methylthiomethyl group, ethoxymethyl group, ethylthiomethyl group, methoxyethoxymethyl group, benzyloxymethyl group, benzylthiomethyl group, phenacyl group, bromophenacyl group, methoxyphenacyl group, methylthiophenacyl group, &agr;-methylphenacyl group, cyclopropylmethyl group, benzyl group, diphenylmethyl group, triphenylmethyl group, bromobenzyl group, nitrobenzyl group, methoxybenzyl group, methylthiobenzyl group, ethoxybenzyl group, ethylthiobenzyl group, piperonyl group, methoxycarbonylmethyl group, ethoxycarbonylmethyl group, n-propoxycarbonylmethyl group, isopropoxycarbonylmethyl group, n-butoxycarbonylmethyl group, t-butoxycarbonylmethyl group and the like.
Examples of the 1-substituted ethyl group include 1-methoxyethyl group, 1-methylthioethyl group, 1,1-dimethoxyethyl group, 1-ethoxyethyl group, 1-ethylthioethyl group, 1-cyclohexyloxyethyl group, 1,1-diethoxyethyl group, 1-phenoxyethyl group, 1-phenylthioethyl group, 1,1-diphenoxyethyl group, 1-benzyloxyethyl group, 1-benzylthioethyl group, 1-cyclopropylethyl group, 1-phenylethyl group, 1,1-diphenylethyl group, 1-methoxycarbonylethyl group, 1-ethoxycarbonylethyl group, 1-n-propoxycarbonylethyl group, 1-isopropox
Kai Toshiyuki
Kobayashi Eiichi
Nishimura Yukio
Shioya Takeo
Baxter Janet
JSR Corporation
Lee Sin J.
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