Copolymer resin, preparation thereof, and photoresist using...

Details Copolymer resin, preparation thereof, and photoresist using... Copolymer resin, preparation thereof, and photoresist using...

1998-12-10

2001-06-19

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, C526S318400, C430S270100

Reexamination Certificate

active

06248847

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to a technique including a process and resulting structure for a copolymer resin for an ultra-shortwave light source such as KrF or ArF. More specifically, it relates to a copolymer resin, where a norbonyl(meth)acrylate unit is introduced to a copolymeric structure for a photo resist. The photo resist can be used in a variety of lithography processes using a KrF (248 nm) or ArF (193) light source which is a light source to be applied in next generation memory elements such as 1G or 4G DRAM integrated circuit chips.
In general, characteristics such as etching resistance, adhesiveness with low light absorption at 193 nm wavelength are often desired for a copolymer resin for ArF. The copolymer resin should also be developable by using, for example, a 2.38 wt % aqueous solution of tetramethylammonium hydroxide (TMAH). It is difficult, however, to synthesize a copolymer resin satisfying some or all these desirable characteristics. Many researches have often focused on studies on a norbolac type resin as a material to increase transparency at 193 nm wavelength and increase etching resistance. Thus, attempts to employ(meth)acrylate resins having high transparency, and to introduce alicyclic compounds to resin side chains in order to overcome limitations of deficient etching resistance, have been suggested. For example, IBM suggested the use of a copolymer resin represented by following chemical formula I:
where R
1
, R
2
and R
3
independently represent hydrogen or methyl.
The copolymer resin represented by chemical formula I unfortunately has increased hydrophobicity. The increased hydrophobicity occurs, in part, from introducing an alicyclic compound to the side chain, which decreases solubility in the developing solution and weakens adhesiveness, so that the compound can be contained in the copolymer resin composition in an amount not more than a certain level. It should be noted that if the alicyclic compound is included at less than the certain level, satisfactory etching resistance cannot generally be achieved. It has been found that, among the conventional alicyclic groups on side chains, which are commonly known, the norbonyl or admantyl group is effective in view of etching resistance. The conventional copolymer resin including formula I has a severe limitation in that adhesive strength decreases by gaining hydrophobicity as the content of the cyclic compound in the resin composition increases.
From the above, it is seen that an improved photo resist that has improved characteristics is highly desirable.
SUMMARY OF THE INVENTION
The present inventors have performed intensive studies to overcome the above problems encountered in conventional photo resist products, and as a result, they found a copolymer resin composition having high transparency at 193 nm wavelength and high etching resistance.
In a specific embodiment, the present copolymer resin is prepared by radical polymerization techniques. These techniques include a variety of steps such as introducing norbonyl(meth)acrylate unit in a copolymer resin for photo resist. An adhesive strength of the resin can be increased by introducing a hydrophilic group in norbonyl group. A significant difference of solubility to the developing solution between the exposed region and non-exposed region can be provided through the processes of introducing a suitable protecting group, exposing, and deprotecting by post-heating step.
In an alternative embodiment, the present invention provides a monomer comprising a 5-hydroxy-6-norbonyl(meth)acrylate derivative. In a further embodiment, the present invention provides a process for preparing the monomer. In still a further embodiment, the present invention provides a copolymer resin comprising 5-hydroxy-6-norbonyl (meth)acrylate derivative and a process for preparing the copolymer resin. Among other aspects, the invention also provides photo resist comprising the copolymer resin or resins. Still further, the present invention provides a process for manufacturing the photo resist and a semiconductor element having a pattern formed by using the photo resist. These and other embodiments will be described throughout the present specification and more particularly below.
The present invention achieves these benefits in the context of known process technology. However, a further understanding of the nature and advantages of the present invention may be realized by reference to the latter portions of the specification and attached drawings.
DETAILED DESCRIPTION OF THE INVENTION
In a specific embodiment, the present invention relates generally to a copolymer resin comprising 5-hydroxy-6-norbonyl(meth)acrylate derivative represented by chemical formula II:
where R represents 2-tert-butoxycarbonyl, 2-carboxylic, 2-hydropyranyloxycarbonyl, 2-hydroxyfuranyloxycarbonyl or 2-ethoxyethyloxycarbonyl; R
1
represents hydrogen or methyl.
The copolymer resin according to the present invention preferably includes copolymers represented by chemical formula III to VII.
(1) Poly[2-tert-butoxycarbonyl-5-hydroxy-6-norbonyl(meth)acrylate/2-carboxylic-5-hydroxy-6-norbonyl (meth)acrylate] copolymer resin (Molecular Weight: 4,000 to 100,000)
[In the formula, R
1
and R
2
independently represent hydrogen or methyl, and x and y independently represent a mole fraction between 0.001 and 0.99.]
(2) Poly[2-tert-butoxycarbonyl-5-hydroxy-6-norbonyl(meth)acrylate/2-hydroxyethyl(meth)acrylic acid/(meth)acrylic acid] copolymer resin (Molecular Weight: 4,000 to 10000)
[In the formula, R
1
, R
2
and R
3
independently represent hydrogen or methyl, and x, y and z independently represent a molar fraction between 0.001 and 0.99.]
(3) Poly[2-hydroxypyranyloxycarbonyl-5-hydroxy-6-norbonyl(meth)acrylate/2-hydroxyethyl(meth)acrylate/(meth)acrylic acid] copolymer resin (Molecular Weight: 4,000 to 100,000)
[In the formula, R
1
, R
2
and R
3
independently represent hydrogen or methyl, and x, y and z independently represent a mole fraction between 0.001 and 0.99.]
(4) Poly[2-hydrofuranyloxycarbonyl-5-hydroxy-6-norbonyl(meth)acrylate/2-hydroxyethyl(meth)acrylate/(meth)acrylic acid] copolymer resin (Molecular Weight: 4,000 to 100,000)
[In the formula, R
1
, R
2
and R
3
independently represent hydrogen or methyl, and x, y and z independently represent a mole fraction between 0.001 and 0.99.]
(5) Poly[2-ethoxyethyloxycarbonyl-5-hydroxy-6-norbonyl(meth)acrylate/2-hydroxyethyl(meth)acrylate/(meth)acrylic acid] copolymer resin (Molecular Weight: 4,000 to 100,000)
[In the formula, R
1
, R
2
and R
3
independently represent hydrogen or methyl, and x, y and z independently represent a mole fraction between 0.001 and 0.99.]
The copolymer resin of formula III according to the present invention can be prepared by reacting 2-tert-butoxycarbonyl-5-hydroxy-6-norbonyl (meth)acrylate with 2-carboxylic-5-hydroxy-6-norbonyl (meth)acrylate in the presence of a conventional polymerization initiator, as illustrated in reaction scheme I:
where R
1
and R
2
independently represent hydrogen or methyl.
The copolymer resin of formula IV according to the present invention can be prepared by reacting 2-tert-butoxycarbonyl-5-hydroxy-6-norbonyl (meth)acrylate with 2-hydroxyethyl (meth)acrylate in the presence of a conventional polymerization initiator, as illustrated in reaction scheme II:
where R
1
, R
2
and R
3
independently represent hydrogen or methyl.
The copolymer resin of formula V according to the present invention can be prepared by reacting 2-hydroxypyranyloxycarbonyl-5-hydroxy-6-norbonyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate and (meth)acrylic acid in the presence of a conventional polymerization initiator, as illustrated in reaction scheme III:
wherein, R
1
, R
2
and R
3
independently represent hydrogen or methyl.
The copolymer resin of formula VI according to the present invention can be prepared by reacting 2-hydrofuranyloxycarbonyl-5-hydroxy-6-norbonyl (meth)acryl

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