Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-08-15
2003-07-15
Ashton, Rosemary (Department: 1752)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S271000, C526S317100, C526S319000, C526S320000
Reexamination Certificate
active
06593441
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photosensitive polymer and to a chemically amplified photoresist composition containing the same.
This application is a counterpart of, and claims priority to, Korean Application No. 99-31060, filed Jul. 29, 1999, the contents of which are incorporated herein by reference.
2. Description of the Related Art
As semiconductor devices become highly integrated, photolithography processes used in the fabrication of such devices must be capable of forming ultra-fine patterns. For example, a sub-quarter micron or smaller sized pattern is needed in a semiconductor memory device having a capacity exceeding 1 Gbit. As such, a photolithography technology has been proposed which employs an argon fluoride (ArF) excimer laser as a new type of light source. This is because the ArF laser exhibits a wavelength (193 nm) which is shorter than the wavelength (248 nm) of a conventional krypton fluoride KrF excimer laser. Therefore, a demand has arisen for chemically amplified photoresist polymers and photoresist compositions which are suitable for use with the ArF excimer laser.
In general, a chemically amplified photoresist composition for an ArF excimer laser should exhibit the following characteristics: (1) transparency at a wavelength of 193 nm; (2) excellent thermal properties (for example, high glass transition temperature); (3) good adhesion to underlying (and overlying) film materials; (4) high resistance to dry etching; and (5) easily capable of being developed using developing solutions which are in widespread use in the manufacture of semiconductor devices, for example, 2.38% by weight of tetramethyl ammonium hydroxide (TMAH).
However, a terpolymer comprising methylmethacrylate, t-butyl methacrylate and methacrylic acid, which is a widely known chemically amplified photoresist polymer for the ArF excimer laser, does not exhibit all of the above-mentioned characteristics. In particular, the terpolymer has a very low resistance to dry etching, a low adhesion to underlying film materials and low wettability for a developing solution.
Recently, attempts have been made to increase the etching resistance of a photosensitive polymer for the ArF excimer laser by introducing alicyclic compounds, for example, isobornyl, adamantyl or tricyclodecanyl group, into the backbone of the polymers. However, these polymers also have several disadvantages. For example, their etching resistance is still not acceptable and their adhesion characteristics to underlying films are still poor, which results in lifting of photoresist patterns.
SUMMARY OF THE INVENTION
It is an objective of the present invention to provide a photosensitive polymer which is capable of being exposed using an ArF excimer laser, and which has an improve etching resistance and an improved adhesion to an underlying film or substrate.
It is another objective of the present invention to provide a chemically amplified photoresist composition containing the photosensitive polymer.
Accordingly, to achieve the above objective, there is provided a photosensitive polymer including a first monomer which is norbornene ester having C
1
to C
12
aliphatic alcohol as a substituent, and a second monomer which is maleic anhydride.
Preferably, the C
1
to C
12
aliphatic alcohol is secondary alcohol.
The photosensitive polymer according to the present invention may further include at least one third monomer selected from the group consisting of norbornene carboxylic acid, norbornene ester having a C
6
to C
20
alicyclic ester having C as a substituent, norbornene ester having an acid-labile group as a substituent, (meth)acrylic acid, (meth)acrylate having C
1
to C
12
aliphatic alcohol as a substituent, (meth)acrylate having an acid-labile group as a substituent, and (meth)acrylate having a C
6
to C
20
alicyclic ester having C as a substituent.
In the case where the third monomer is norbornene ester having a C
6
to C
20
alicyclic ester having a C group or (meth)acrylate having a C
6
to C
20
alicyclic ester as a substituent, the first monomer may be norbornene having C
1
to C
12
aliphatic alcohol as a substituent, norbornene carboxylic acid, norbornene having C
1
to C
12
aliphatic ester having C group having carboxy group pendent thereto as a substituent, or norbornene having C
1
to C
12
aliphatic ester having a C group having a carboxylic anhydride group pendent thereto as a substituent.
According to another aspect of the present invention, there is provided a photosensitive polymer including, in addition to the first and second monomers, a third monomer selected from the group consisting of norbornene carboxylic acid, norbornene ester having C
6
to C
20
aliphatic ester having a C group as a substituent and norbornene ester having an acid-labile group as a substituent, and a fourth monomer selected from the group consisting of (meth)acrylic acid, (meth)acrylate having C
1
to C
12
aliphatic alcohol as a substituent, (meth)acrylate having an acid-labile group as a substituent and (meth)acrylate having an aliphatic ester having a C group as a substituent.
In the case where the third monomer is (meth)acrylate having C
6
to C
20
alicyclic ester having a C group as a substituent, the first monomer may be norbornene having C
1
to C
12
aliphatic alcohol as a substituent, norbornene carboxylic acid, norbornene having C
1
to C
12
aliphatic ester having a C group having carboxy group pendent thereto as a substituent, norbornene having C
1
to C
12
aliphatic ester having a C group having a carboxylic anhydride group pendent thereto as a substituent, and norbornene ester having C
1
to C
12
aliphatic alcohol having a carboxylic anhydride group pendent thereto as a substituent.
Also, the present invention provides photosensitive polymer including a first monomer selected from the group consisting of norbornene having C
1
to C
12
aliphatic alcohol as a substituent, norbornene carboxylic acid, norbornene having C
1
to C
12
aliphatic ester having a C group having carboxy group pendent thereto as a substituent, norbornene having C
1
to C
12
aliphatic ester having a C group having a carboxylic anhydride group pendent thereto as a substituent, and norbornene ester having C
1
to C
12
aliphatic alcohol having a carboxylic anhydride group pendent thereto as a substituent, a second monomer which is maleic anhydride, a third monomer which is norbornene ester having an acid-labile group as a substituent, and a fourth monomer which is norbornene ester having C
6
to C
20
alicyclic ester having a C group as a substituent.
To accomplish another object of the present invention, there is provided a chemically amplified photoresist composition including one or more photosensitive polymers each having an average-weight molecular weight of 3,000 to 100,000, and selected from the group consisting of first through sixth photosensitive polymers, and a photoacid generator contained in an amount of 1 to 15% by weight based on the total weight of the one or more photosensitive polymers.
The chemically amplified photoresist composition may further include 1 to 50% by weight of a dissolution inhibitor based on the total weight of the one or more photosensitive polymers. Also, the chemically amplified photoresist composition may further include 0.01 to 2.0% by weight of an organic base based on the total weight of the photosensitive polymer.
The photosensitive polymer according to the present invention has a cyclic backbone, and a hydroxy group is bonded to the backbone. Thus, the etching resistance of the photoresist composition containing the same is large and an adhesion to an underlying film is excellent. In particular, in the case where a secondary alcohol group is bonded to the backbone, the polymer is chemically stable so that it can be stored for a long period of time.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A photosensitive polymer and a chemically amplified photoresist composition containing the same according to the present invention will now be described. Also,
Choi Sang-jun
Jung Dong-won
Lee Si-hyeung
Lee Sook
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