Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Utility Patent
1999-09-09
2001-01-02
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S331000, C430S905000, C430S909000, C430S270100, C430S914000
Utility Patent
active
06168909
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to material and method for forming a resist pattern on a semiconductor substrate during a process of fabricating a semiconductor integrated circuit device. More specifically, the present invention relates to material and method for forming a fine-line resist pattern by exposing a chemically amplified resist to exposing radiation with a wavelength of 160 nm or less, such as vacuum ultraviolet radiation (VUV).
In a known method for forming a fine-line resist pattern by exposing a chemically amplified resist, deposited on a semiconductor substrate, to exposing radiation with a short wavelength, a KrF or ArF excimer laser (wavelength: 248 nm and 193 nm, respectively) is used as a source of the exposing radiation. As for the KrF excimer laser, a phenol resin was previously used as a resist material. On the other hand, as for the ArF excimer laser, an acrylic acid resin will be used as a resist material.
To form a fine-line resist pattern with a line width of 0.1 &mgr;m or less, however, an exposing radiation such as vacuum ultraviolet radiation with an even shorter wavelength than that of the KrF or ArF excimer laser, e.g., F
2
and Kr
2
excimer lasers, which both oscillate at wavelengths shorter than 160 nm (i.e., 157 and 147 nm, respectively), is preferably used.
Nevertheless, a chemically amplified resist containing a phenol or acrylic acid resin is highly absorptive with respect to the exposing radiation with a wavelength of 160 nm or less. Thus, it is difficult to apply such a material to a pattern forming method, in which a resist film is exposed to the radiation with a wavelength of 160 nm or less.
SUMMARY OF THE INVENTION
An object of the present invention is providing a material applicable to forming a resist pattern using the exposing radiation with a wavelength of 160 nm or less.
Another object of the present invention is providing a method for forming a resist pattern using such a material.
To achieve these objects, the present inventors performed intensive research to know the reason why a chemically amplified resist containing a phenol or acrylic acid resin is highly absorptive to the exposing radiation with a wavelength of 160 nm or less. As a result, we arrived at the conclusion that the high absorptance of the phenol or acrylic acid resin results from their double bonds of atoms like C═C and C═O.
Based on this finding, according to the present invention, a chemically amplified resist, which is based on a resin including no or at least substantially no double bonds of atoms like C═C and C═O, is used as a material for forming a resist pattern.
A first exemplary resin including no double bonds of atoms may be a derivative of a material represented by the following general chemical Formula 1:
where at least one of the portions encircled by one-dot chains A and B should exist. That is to say, the material may include the portion A but not the portion B; include the portion B but not the portion A; or include both of these portions A and B.
In Formula 1, X may be either contained or not contained. If X is contained, then the X is N or C. Y
1
and Y
2
are of either the same or different species. At least one of Y
1
and Y
2
is a hydrophilic group (i.e., —OH or —NH
2
). Otherwise, Y
1
or Y
2
is H. Z
1
and Z
2
are of either the same or different species and are —OH, —CH
3
or H. n is an integer equal to or larger than 1. And p and q are 0, 1, 2 or 3.
Examples of the first resin represented by Formula 1 include poly(vinyl alcohol), vinylamine polymer and poly(N-hydroxyethylaziridine).
Polyvinyl alcohol is a version represented by Formula 1, in which X is not contained, p is 0 and Y
1
is —OH (i.e., A is —OH).
Vinylamine polymer is another version represented by Formula 1, in which X is not contained, p is 0 and Y
1
is —NH
2
(i.e., A is —NH
2
).
Poly(N-hydroxyethylaziridine) is still another version represented by Formula 1, in which X is N, p is 0 and Y
1
is —H (i.e., A is —H), q is 2 and Y
2
is —OH.
A second exemplary resin including no double bonds of atoms may be a derivative of a material represented by the following general chemical Formula 2:
where at least one of Y
1
and Y
2
is —OH or —NH
2
; Y
1
or Y
2
, which is neither —OH nor —NH
2
, is H or an alkyl group; and each of n and m is an integer equal to or larger than 1. Examples of the second resin represented by Formula 2 include polyhydroxycyclohexene.
A version of Formula 2, in which m is 4, may be represented by the following general chemical Formula 3:
where one or two of Y
1
, Y
2
, Y
3
and Y
4
is/are —OH or NH
2
.
A derivative of the resin represented by Formula 1, 2 or 3 may be obtained by substituting a chain or cyclic alkyl or alkoxyalkyl group for part or all of OH or NH
2
.
Specifically, a material for forming a pattern according to the present invention is a chemically amplified resist containing: a resin; and an acid generator that generates an acid when exposed to exposing radiation. The resin includes a derivative of poly(vinyl alcohol), a derivative of a vinylamine polymer, a derivative of poly(N-hydroxyethylaziridine), a derivative of polyhydroxycyclohexene or a copolymer including at least one of these derivatives.
A method for forming a resist pattern according to the present invention includes the step of forming a resist film on a substrate by coating the substrate with a chemically amplified resist. The chemically amplified resist contains a resin and an acid generator that generates an acid when exposed to exposing radiation. The resin includes a derivative of poly(vinyl alcohol), a derivative of a vinylamine polymer, a derivative of poly(N-hydroxyethylaziridine), a derivative of polyhydroxycyclohexene or a copolymer including at least one of these derivatives. The method further includes the steps of: exposing the resist film to exposing radiation with a wavelength of 160 nm or less; and forming the resist pattern with a line width of 0.1 &mgr;m or less by developing the resist film exposed.
In the material and method for forming a pattern according to the present invention, examples of the resin that contains a derivative of poly(vinyl alcohol), a derivative of a vinylamine polymer, a derivative of poly(N-hydroxyethylaziridine), a derivative of polyhydroxycyclohexene or a copolymer including at least one of these derivatives include: any of these derivatives; a copolymer or mixture including at least one of these derivatives; a copolymer including at least one of these derivatives and poly(vinyl phenol), poly(methacrylic acid) or poly(acrylic acid); and a copolymer including at least one of these derivatives and a derivative of poly(vinyl phenol), poly(methacrylic acid) or poly(acrylic acid).
According to the present invention, the chemically amplified resist is based on a resin composed of monomer units including substantially no double bonds of atoms such as C═C or C═O, and therefore shows excellent transmittance to exposing radiation with a wavelength of 160 nm or less. Thus, in the exposed portions of the resist film, the exposing radiation can reach the bottom thereof. As a result, an acid is generated from the acid generator downward, i.e., from the surface toward the bottom of the resist film, with a lot more certainty. Consequently, a resist pattern can be formed exactly in its desired shape.
Examples of the acid generator include: onium salts such as sulfonium salts and iodonium salts; ester sulfonates; and diazodisulfonylmethanes.
Also, the material for forming a pattern may contain a solvent that can dissolve the resin, a basic compound such as an amine, or an additive such as a surfactant if necessary.
REFERENCES:
patent: 5506088 (1996-04-01), Nozaki et al.
patent: 10115922 (1998-05-01), None
Yamana 1998: 275000, File HCAPLUS of STN Database Service, Chemical Abstracts, American Chemical Society, 1998, p. 105-106 (English Abstract of JP10115922), May 6, 1998.*
Baxter Janet
Lee Sin J.
Matsushita Electric - Industrial Co., Ltd.
Nixon & Peabody LLP
Robinson Eric J.
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