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
1999-08-26
2001-09-18
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S325000, C430S315000, C430S926000, C526S271000, C526S262000
Reexamination Certificate
active
06291131
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to novel monomers for preparing photoresist polymers, photoresist polymers and photoresist compositions using the same. More specifically, it relates to such monomers, polymers and compositions which are usable in a photolithography process employing a KrF (248 nm), ArF (193 nm), E-beam, ion-beam or EUV light source, in the preparation of a microcircuit of a highly integrated semiconductor element.
BACKGROUND OF THE INVENTION
Recently, chemical amplification type DUV (deep ultra violet) photoresists have been investigated as a means for achieving high sensitivity in micro processes for preparing a semiconductor device. These photoresists are generally prepared by blending a photoacid generator with photoresist polymer matrix macromolecules having acid labile substituents in an organic solvent to form a photoresist composition.
According to the reaction mechanism of such photoresists, the photoacid generator generates acid when it is irradiated by the light source, and substituents on the main chain or branched chain of the matrix macromolecule in the exposed portion react with the generated acid to be decomposed or cross-linked, thereby considerably altering the polarity of the macromolecule. As a result, there is a solubility difference in the developing solution between the exposed area and the unexposed area. For example, in case of a positive photoresist, the main or branched chain of the matrix macromolecule is decomposed by acid in the exposed area and is removed by being dissolved in the developing solution. On the other hand, in the case of the unexposed area, the original structure of the macromolecular compound is maintained without being dissolved in the developing solution. As a result, the image of a mask is formed on the substrate as a positive image. In the lithography process, resolution depends upon the wavelength of the light source—the shorter the wavelength, the more minute the pattern that can be formed.
A suitable photoresist polymer generally requires excellent etching resistance, heat resistance and adhesiveness, and, in particular, when a photoresist is used for lithography processes employing ArF light source, it should be developable in 2.38% aqueous tetramethylammonium hydroxide (TMAH) solution. However, it is very difficult to synthesize a polymer that satisfies all these requisites. For example, a polymer having a polyacrylate main chain can be easily synthesized, but it has poor etching resistance and difficulties in the developing process. Etching resistance can be enhanced if an alicyclic monomer is introduced into the main chain. However, it is very difficult to synthesize a polymer having a main chain comprised of all alicyclic monomers.
Research to solve the problems described above has been widely performed in the past. In the case of forming an ultramicro pattern of 0.10 micron or less, the thickness of the photoresist layer must be 0.3 micron or less, but no photoresist has been developed to date which is resistant to etching gas in such a thin layer. In other words, any photoresist composition developed up to the present shows insufficient adhesiveness to the substrate and etching resistance when it is applied as a photoresist layer for a semiconductor element requiring resolution of 0.1 &mgr;m or less.
SUMMARY OF THE INVENTION
An object of the present invention is to provide novel monomers which are suitable for forming polymers which can be used as photoresists in the formation of high integrity integrated circuits, and processes for preparing the same.
Another object of the present invention is to provide novel photoresist polymers comprising said monomers, and a process for preparing the same.
Still another object of the present invention is to provide photoresist compositions containing the novel polymers, and a process for preparing the same.
In order to achieve these objects, the present invention provides a novel monomer represented by the following Chemical Formula 1:
wherein, X and Y individually represent oxygen, sulfur, CH
2
or CH
2
CH
2
; n represents an integer of 1 to 5; and R
1
, R
2
, R
3
and R
4
individually represent hydrogen, C
1
-C
10
alkyl having substituent(s) on its main or branched chain, C
1
-C
10
ester having substituent(s) on its main or branched chain, C
1
-C
10
ketone having substituent(s) on its main or branched chain, C
1
-C
10
carboxylic acid having substituent(s) on its main or branched chain, C
1
-C
10
acetal having substituent(s) on its main or branched chain, C
1
-C
10
alkyl having substituent(s) including one or more hydroxyl group(s) on its main or branched chain, C
1
-C
10
ester having substituent(s) including one or more hydroxyl group(s) on its main or branched chain, C
1
-C
10
ketone having substituent(s) including one or more hydroxyl group(s) on its main or branched chain, C
1
-C
10
carboxylic acid having substituent(s) including one or more hydroxyl group(s) on its main or branched chain, or C
1
-C
10
acetal having substituent(s) including one or more hydroxyl group(s) on its main or branched chain; provided that at least one of R
1
to R
4
represent(s) —COO—R′—OH wherein R′ is a linear or branched chain alkyl group with or without substituent(s) on its linear or branched chain.
Further, in order to achieve another object of the present invention, a novel photoresist polymer is provided which comprises repeating units derived from the monomer of Chemical Formula 1. Preferred polymers of the present invention contain repeating units of Chemical Formula 1 in addition to one or more other repeating units, as represented by the following Chemical Formula 300:
wherein, X, Y, V, W, U and Z individually represent oxygen, sulfur, CH
2
or CH
2
CH
2
; n represents an integer from 1 to 5, m and 1 individually represent an integer of 0 to 5; R
1
to R
12
individually represent hydrogen, C
1
-C
10
alkyl having substituent(s) on its main or branched chain, C
1
-C
10
ester having substituent(s) on its main or branched chain, C
1
-C
10
ketone having substituent(s) on its main or branched chain, C
1
-C
10
carboxylic acid having substituent(s) on its main or branched chain, C
1
-C
10
acetal having substituent(s) on its main or branched chain, C
1
-C
10
alkyl having substituent(s) including one or more hydroxyl group(s) on its main or branched chain, C
1
-C
10
ester having substituent(s) including one or more hydroxyl group(s) on its main or branched chain, C
1
-C
10
ketone having substituent(s) including one or more hydroxyl group(s) on its main or branched chain, C
1
-C
10
carboxylic acid having substituent(s) including one or more hydroxyl group(s) on its main or branched chain, or C
1
-C
10
acetal having substituent(s) including one or more hydroxyl group(s) on its main or branched chain; a, b, c, d and e individually represent polymerization ratio of each comonomer that is present; and R
13
is a linear or branched alkyl group; provided that at least one of R
1
to R
4
represent(s) —COO—R′—OH wherein R′ is an alkyl group having substituent(s) on its linear or branched chain, at least one of R
5
to R
8
represent(s) —R″—COO—R wherein R″ is a linear or branched alkyl group and R is an acid labile protective group, and at least one of R
9
to R
12
represent(s) —R′″—COOH wherein R′″ is a linear or branched alkyl group.
In order to achieve still another object, the present invention provides a photoresist composition that comprises said photoresist copolymer, a photoacid generator and an organic solvent.
DETAILED DESCRIPTION OF THE INVENTION
Novel Photoresist Monomers
The present inventors have found the polyalicyclic monomers of the invention, especially, polyalicyclic monomers which contain oxygen or sulfur in the ring and one or more hydroxyl group(s) as substituent(s), as represented by Chemical Formula 1, provide photoresist copolymers having excellent etching resistance as well as excellent adhesiveness to a substrate.
As previously stated, the monomers of the pr
Baik Ki Ho
Jung Jae Chang
Jung Min Ho
Kong Keun Kyu
Lee Geun Su
Baxter Janet
Clarke Yvette M.
Hyundai Electronics Industries Co,. Ltd.
Townsend and Townsend / and Crew LLP
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