Photoresist monomer having hydroxy group and carboxy group,...

Details Photoresist monomer having hydroxy group and carboxy group,... Photoresist monomer having hydroxy group and carboxy group,...

1999-08-26

2002-06-25

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S282000, C526S258000, C526S271000, C526S272000, C526S219600, C430S296000, C430S270210, C430S192000

Reexamination Certificate

active

06410670

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to novel monomers used for preparing a photoresist copolymer, copolymers thereof, and photoresist compositions prepared therefrom. More specifically, it relates to such novel monomers, copolymers and photoresist compositions suitable to be exposed to light in the far ultraviolet region of the spectrum.
BACKGROUND OF THE INVENTION
A photosensitive film for use with far ultraviolet light, in particular, for ArF radiation, must satisfy several requisites; it must have low light absorbance at a wavelength of 193 nm, excellent etching resistance and adhesiveness to a substrate, and be developable in an aqueous solution of 2.38% or 2.6% tetramethylammonium hydroxide (hereinafter, abbreviated as TMAH). Up to the present time, researchers have focused on searching for a substance having as high transparency and etching resistance at 193 nm as novolac resins. For example, researchers at the Bell Labs Research Center have enhanced etching resistance of photoresist copolymers by adding an alicyclic unit to the main chain. In addition, researchers at Fujitsu of Japan and Sipri of the United States are actively investigating methacrylate and acrylate compounds as photoresist polymers. However, these techniques have not solved the problem of etching resistance, and involve increased production costs resulting from the introduction of alicyclic groups into the polymer. In addition, the low adhesiveness exhibited by most prior art photoresists is disadvantageous in that photolithographic patterns cannot be established with integrated L/S patterns of 150 nm or less.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the problems described above, and to provide novel monomers which can be used to form copolymers which have excellent adhesiveness and sensitivity, and which can be easily produced at low production cost, and to provide a process for preparing the monomers.
Another object of the present invention is to provide copolymers of the novel monomers, and a process for preparing the same.
Another object of the present invention is to provide photoresist compositions using the copolymers and a process for preparing the same.
Still another object of the present invention is to provide a semiconductor element produced by using the photoresist composition.
The present invention provides a novel compound represented by following Chemical Formula 1:
wherein,
R is substituted or non-substituted linear or branched (C
1
-C
10
)alkyl, substituted or non-substituted (C
1
-C
10
)ether, substituted or non-substituted (C
1
-C
10
)ester, or substituted or non-substituted (C
1
-C
10
)ketone,
X and Y are independently CH
2
, CH
2
CH
2
, oxygen or sulfur; and
i is 0 or an integer of 1 to 2.
In order to achieve other technical objects, photoresist copolymer comprising repeating units of the monomer of Formula 1 are provided by another embodiment of the present invention. Preferred copolymers are represented by following Chemical Formulas 100 and 100a:
wherein,
R is substituted or non-substituted linear or branched (C
1
-C
10
)alkyl, substituted or non-substituted (C
1
-C
10
)ether, substituted or non-substituted (C
1
-C
10
)ester, or substituted or non-substituted (C
1
-C
10
)ketone;
X, Y, V and W are independently CH
2
, CH
2
CH
2
, oxygen or sulfur;
i and j are independently 0 or an integer of 1 to 2;
R* is an acid-reactable group; and
a, b and c represent the polymerization ratio of the monomers.
In the case of the chemical formula 100, it is preferred that a:b:c=(0.01-0.2): (0.1-0.4): 0.5 in molar equivalent ratio.
The photoresist composition according to the present invention comprises (i) a photoresist copolymer according to the present invention, a photoacid generator and a conventional organic solvent.
Hereinafter, the present invention will be described in detail.
DETAILED DESCRIPTION
Compounds of Chemical Formula 1 have been found to be particularly useful for preparing chemically amplified photoresist copolymers. Compounds of Chemical Formula 1 have a HYDROXY group which can enhance adhesiveness of the photoresist to a wafer substrate and a carboxylic acid group which can contribute to the enhancement of photo-sensitivity at the same time. In addition, the compounds can be simply synthesized without toxic odors and are readily crystallized in water without using any complicated separating means such as distillation or column chromatography. Thus, compounds of the present invention are advantageous in mass production at low cost.
In preferred compounds of Chemical Formula 1, R is represented by the following Chemical Formula 1a:
—(CH
2
)
m
—Z—(CH
2
)
n
—  <Chemical Formula 1a>
wherein
Z is a moiety of the formula —C(R
1
)(R
2
)— or oxygen;
R
1
and R
2
are independently H or an (C
1
-C
5
)alkyl; and
m and n are independently 0 or an integer of 1 to 5.
The photoresist monomer according to the present invention can be prepared by reacting (i) a di-alcohol such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol and diethylene glycol and (ii) an anhydride such as 5-norbornene-2,3-dicarboxylic anhydride and exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride, in an organic solvent such as tetrahydrofuran, dimethylformamide, dioxane, benzene and toluene.
For example, the compound represented by the following Chemical Formula 2, one of the compounds represented by the above Formula 1, can be obtained by reacting a compound of Chemical Formulas 2a and 2b in the presence of an acid catalyst or a base:
wherein,
Y is CH
2
, CH
2
CH
2
, oxygen or sulfur;
Z is a moiety of the formula —C(R
1
)(R
2
)— or oxygen;
R
1
and R
2
are independently H or an (C
1
-C
5
)alkyl; and
m and n are independently 0 or an integer of 1 to 5.
The compound of Chemical Formula 2a may be used in the same amount or in an excess amount relative to the compound of Chemical Formula 2b.
NaH, KH, CaH
2
, Na
2
CO
3
, LDA (lithium diisopropylamide) or the like may be used as a base, and sulfuric acid, acetic acid or nitric acid may be used as an acid catalyst.
Novel monomers according to the present invention (the compounds represented by Chemical Formula 1) can also be prepared by a Diels-Alder reaction.
For example, the compound represented by the above chemical formula 2 can be prepared by following Reaction Schemes (1) and (2) below:
wherein
Y is CH
2
, CH
2
CH
2
, oxygen or sulfur;
Z is a moiety of the formula —C(R
1
)(R
2
)— or oxygen;
R
1
and R
2
are independently H or an (C
1
-C
5
)alkyl; and
m and n are independently 0 or an integer of 1 to 5.
That is, first, the intermediate material is obtained by reacting maleic anhydride and di-alcohol in an organic solvent such as benzene, tetrahydrofuran, dimethylformamide or dioxane in the presence of an acid catalyst, as shown in the Reaction Scheme 1, and then, the final product material is obtained by a Diels-Aider reaction which is performed in an organic solvent such as benzene and tetrahydrofuran, as shown in the Reaction Scheme 2.
Preferred photoresist copolymers according to the present invention comprise repeating units of a compound of Chemical Formula 1 as a first comonomer and a compound of the following Chemical Formula 3 as the second comonomer:
wherein,
V and W are independently CH
2
, CH
2
CH
2
, oxygen or sulfur;
j is 0 or an integer of 1 to 2; and
R* is an acid reactable group.
In the Chemical Formula 3, the R* is released when it is reacted with the acid produced by the photoacid generator in the photoresist composition. Thus, while the photoresist polymer in exposed regions of the photoresist layer becomes soluble in the developing solution, the polymer in the unexposed regions is not dissolved in the developing solution because acid is not generated therein and therefore the acid-reactable groups are still bound to the photoresist polymer. As the result, a predetermined pattern is formed.
Accordingly, the compounds of Chemical Formula 3 have a role in enhancing the photosensitivity of the phot

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